Preface

The goals and principles of standardization in the Russian Federation are established by Federal Law of December 27, 2002 No. 184-FZ “On Technical Regulation”, and the rules for applying national standards of the Russian Federation are GOST R 1.0 - 2004 “Standardization in the Russian Federation. Basic provisions" Information about the standard 1. PREPARED by the Open Joint Stock Company "Scientific Research Center for Control and Diagnostics of Technical Systems" (JSC "SRC KD") based on its own authentic translation of the standard specified in paragraph 4 2. INTRODUCED by the Technical Committee for Standardization TC 457 “Air quality” 3. APPROVED AND ENTERED INTO EFFECT by Order of the Federal Agency for Technical Regulation and Metrology dated December 27, 2007 No. 590-st 4. This standard is identical to the international standard ISO 16000-3:2001 “Air of enclosed spaces. Part 3. Determination of formaldehyde and other carbonyl compounds. Active sampling method" (ISO 16000-3:2001 "Indoorair - Part 3: Determination of formaldehyde and other carbonyl compounds - Active sampling method"). When applying this standard, it is recommended to use, instead of reference international standards, the corresponding national standards, information about which is given in Additional Appendix C 5. INTRODUCED FOR THE FIRST TIME Information about changes to this standard is published in the annually published information index “National Standards”, and the text of changes and amendments - in the monthly published information indexes “National Standards”. In case of revision (replacement) or cancellation of this standard, the corresponding notice will be published in the monthly published information index “National Standards”. Relevant information, notifications and texts are also posted in the public information system - on the official website of the Federal Agency for Technical Regulation and Metrology on the Internet

1. Scope of application 2. Regulatory references 3. Essence of the method 4. Limitations and interfering substances 4.1. General provisions 4.2. Interfering influence of ozone 5. Safety requirements 6. Equipment 7. Reagents 8. Preparation of reagents and cartridges 8.1. Purification of 2,4-dinitrophenylhydrazine 8.2. Preparation of DNPH-formaldehyde derivative 8.3. Preparation of stock solutions of DNPH-formaldehyde derivative 8.4. Preparation of cartridges with DNPH applied to silica gel 9. Methodology 9.1. Sampling 9.2. Blank samples 9.3. Sample analysis 10. Calculation of measurement results 11. Performance criteria and quality control of measurement results 11.1. General provisions 11.2. Standard Operating Procedures 11.3. HPLC system performance 11.4. Sample loss 12. Precision and uncertainty Appendix A (informative) Precision and uncertainty Appendix B (informative) Melting points of DNPH derivatives of carbonyl compounds Appendix C (informative) Information on the compliance of national standards of the Russian Federation with reference international standards Bibliography

Introduction

This standard applies to the analysis of indoor air for sampling purposes in accordance with ISO 16000-2. The standard is used to determine the content of formaldehyde and other carbonyl compounds. The standard was tested against 14 aldehydes and ketones. Formaldehyde is the simplest carbonyl compound consisting of one carbon atom, one oxygen atom and two hydrogen atoms. In its pure form in a monomolecular state, it is a colorless, pungent odor, chemically active gas. Formaldehyde is used in the production of urea-formaldehyde polymers, adhesives and insulating foams. The main source of formaldehyde in the air of enclosed spaces is its release from particle boards and insulating materials used in construction. Sampling for formaldehyde determination is accomplished by pumping air through a reactive medium, which produces a derivative compound with a lower vapor pressure that is more effectively retained in the sampling device and can be more easily analyzed. This standard establishes a procedure for the determination of formaldehyde and other carbonyl compounds, which is based on the reaction of these compounds with 2,4-dinitrophenyl-hydrazine deposited on a sorbent to convert them into the corresponding hydrazones, which can be extracted and their content measured with high sensitivity, precision and accuracy. The methodology given in this standard is also applicable to the determination of other carbonyl compounds released into the air from solvents, adhesives, cosmetics, and other sources. The sampling methodology given in this standard is based on the TO-11 A method [1]. When applying the methodology established in this standard, it should be taken into account that formaldehyde and some other carbonyl compounds are highly toxic substances [2].

NATIONAL STANDARD OF THE RUSSIAN FEDERATION

Date of introduction - 2008-10-01

1 area of ​​use

This standard specifies a method for the determination of formaldehyde (HCHO) and other carbonyl compounds 1) (aldehydes and ketones) in air. The method used for the determination of formaldehyde, after appropriate modification, is used for the detection and quantification of other carbonyl compounds (at least 13 compounds). The method is used for the determination of formaldehyde and other carbonyl compounds in the mass concentration range from approximately 1 μg / m 3 to 1 mg / m 3. Using the method given in the standard, a time-averaged sample is obtained. The method can be used for both long-term (from 1 to 24 hours) and short-term (from 5 to 60 minutes) air sampling to determine the formaldehyde content in it. This standard specifies a method for collecting and analyzing air samples to determine the content of formaldehyde and other carbonyl compounds by collecting them from the air using 2,4-dinitrophenylhydrazine (DNPH) cartridges and subsequent analysis by high-performance liquid chromatography (HPLC) with ultraviolet ( UV) detector [1], [3]. The method given in the standard is designed specifically for the collection and analysis of samples to determine the content of formaldehyde in air using a cartridge filled with an adsorbent, followed by HPLC. The method is also applicable to determine the content of other aldehydes and ketones in the air. 1) This standard gives common names of compounds instead of the names according to the ID PAC nomenclature given in brackets: formaldehyde (methanal); acetaldehyde (ethanal); acetone (propane -2-one); butyraldehyde (butanal); crotonaldehyde (2-butenal); isovaleric aldehyde (3-methylbutanal); propionaldehyde (propanal); m - toluylaldehyde (3-methylbenzaldehyde); o - toluylaldehyde (2-methylbenzaldehyde); p - toluylaldehyde (4-methylbenzaldehyde); valeraldehyde pentanal. The method given in this standard is used for the determination of the following carbonyl compounds:

2. Normative references

This standard uses normative references to the following standards: ISO 9001:2000 Quality management systems. Requirements ISO 16000-1 Air in confined spaces. Part 1. Sampling. General ISO 16000-2 Indoor air. Part 2: Methodology for sampling formaldehyde ISO 16000-4 Indoor air. Part 4. Determination of formaldehyde. Diffusion sampling method ISO 17025:2005 General requirements for the competence of testing and calibration laboratories

3. Essence of the method

This standard specifies a method for pumping air through a cartridge containing silica gel coated with DNPH. The method is based on a specific reaction of the carbonyl group of the analyte with DNPH in the presence of an acid to form stable derivatives (Figure 1). The parent aldehydes and ketones are determined from their DNPH derivatives by HPLC using a UV or diode array detector. Other carbonyl compounds can be determined by the specified detection methods according to 9.3.5. This standard provides guidance for the preparation of sampling cartridges based on commercially available chromatography cartridges containing silica gel by injecting each cartridge with acidified DNPH. It is recommended to use commercially produced cartridges containing silica gel coated with DNPH, since they are more standardized and have a low level of blank readings. However, commercially produced cartridges must be tested to ensure compliance with this standard before use. Another advantage of commercially available cartridges is that they contain silica gel with a larger particle size, which results in less air pressure drop within the cartridge. Such low pressure drop cartridges may be useful for sampling air in the breathing zone using battery operated pumps.

R is an alkyl or aromatic group for ketones, or H for aldehydes; R" is an alkyl or aromatic group for ketones.

Figure 1 - Scheme of the reaction of carbonyl compounds with DNPH

4. Restrictions and interfering substances

4.1. General provisions

The requirements of this standard have been confirmed by sampling air at a flow rate of no more than 1.5 l/min. This flow limitation is due to the high pressure drop (more than 8 kPa at a flow rate of 1.0 L/min) through the user-prepared silica gel cartridge, which has a particle size of 55 to 105 µm. These cartridges are not compatible with battery-operated pumps used for sampling air in the breathing zone (for example, for industrial hygiene purposes). To collect and analyze air samples to determine the formaldehyde content in it, a specific sampling technique for a solid sorbent is used. Difficulties may arise in the implementation of the method due to the presence of some isomers of aldehydes or ketones, which cannot be separated using HPLC when analyzing other aldehydes and ketones. Interfering substances are also organic compounds that have the same retention time and significant absorption at a wavelength of 360 nm as DNPH, a formaldehyde derivative. The influence of interfering substances can be eliminated by changing the separation conditions (for example, using different HPLC columns or changing the composition of the mobile phase). The problem of formaldehyde contamination of DNPH often arises. In such cases, DNPH is purified by repeated recrystallization from acetonitrile, pure in the UV region of the spectrum. Recrystallization is carried out at temperatures from 40 °C to 60 °C by slowly evaporating the solvent to obtain crystals of maximum size. The content of carbonyl compound impurities in DNPG is preliminarily determined by HPLC, and it should be no more than 0.15 μg per cartridge. Sampling cartridges coated with DNPH should not be exposed to direct sunlight to avoid the appearance of spurious peaks [4]. This technique is not used to accurately quantify acrolein in air. Inaccurate results in the quantification of acrolein may be due to the appearance of several peaks of its derivatives and instability of peak ratios [5]. NO 2 reacts with DNPH. High MO 2 content (for example, when using gas stoves) can lead to problems, since the retention time of its DNPG derivative can coincide with the retention time of DNPH derivative formaldehyde, depending on the HPLC column and analysis parameters [6], [7] , [ 8].

4.2. Interfering influence of ozone

Special measures should be taken if high levels of ozone are expected in the air in the sampling area (for example, from office copying equipment). The presence of ozone leads to an underestimation of the result of determining the content of analyzed substances, since in the cartridge it reacts with both DNPH and its derivatives (hydrazones) [9]. The degree of interference depends on changes in ozone and carbonyl compounds over time, as well as on the duration of sampling. A significant underestimation of the determination result (negative interfering effect of ozone) was observed even at mass concentrations of formaldehyde and ozone corresponding to clean atmospheric air (2 and 80 μg/m3, respectively) [10]. During the analysis, the presence of ozone in a sample can be judged by the appearance of new compounds whose retention time is less than the retention time of formaldehyde hydrazone. Figure 2 shows chromatograms of formaldehyde-enriched air with and without ozone. The simplest solution to reduce the interfering effects of ozone is to remove it before the bleed air reaches the cartridge. This can be achieved by using an ozone trap or ozone scrubber installed in front of the cartridge. Commercially produced ozone traps and scrubbers are used. Also, an ozone trap can be made from a copper tube 1 m long, with an external diameter of 0.64 cm and an internal diameter of 0.46 cm, which is filled with a saturated aqueous solution of potassium iodide, left for several minutes (for example, 5 minutes), then the solution is drained and the tube dried in a stream of clean air or nitrogen for approximately 1 hour. The throughput of such an ozone removal device is approximately 200 µg/m 3 per hour. The analyzed aldehydes (formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde and n-toluylaldehyde), introduced into the sample air flow in a dynamic mode, passed through the ozone trap with virtually no losses [11]. Commercially produced ozone scrubbers, which are a cartridge filled with granular potassium iodide weighing from 300 to 500 mg, are also effective for ozone removal [12].

X - unknown compound; 0 - DNPH; 1 - formaldehyde; 2 - acetaldehyde; a - with ozone; b - ozone-free

Figure 2 - Examples of chromatograms for formaldehyde in an air stream with ozone and without ozone

5. Safety requirements

5.1. This standard does not specify all the safety requirements that must be observed in its application. The user of the standard must develop appropriate safety and health measures taking into account the requirements of legal acts. 5.2. DNPH is explosive when dry and should be handled with extreme care. It is also toxic, mutagenic in some tests, and an irritant to the eyes and skin. 5.3. Perchloric acid with a mass fraction of less than 68% is stable and does not oxidize at room temperature. However, it easily dehydrates at temperatures above 160°C, which can lead to an explosion when it comes into contact with alcohols, wood, cellulose and other oxidizable materials. It should be stored in a cool, dry place and used with extreme care only in a fume hood.

6. Equipment

In addition to the usual laboratory equipment, the following equipment is used. 6.1. Sampling 6.1.1. Sampling cartridge filled with silica gel, coated with DNPH, prepared in accordance with Section 8 or commercially available. The cartridge must contain at least 350 mg of silica gel, and the mass fraction of DNPH applied to it must be at least 0.29%. The ratio of the diameter of the silica gel layer to its thickness should be no more than 1:1. The permissible load of the cartridge for formaldehyde determination must be at least 75 μg, and the collection efficiency must be at least 95% at an air flow of 1.5 l/min. Sampling cartridges are commercially available with low blank levels and high performance. Note - At an air flow of 1.5 l/min, the pressure drop in the user-prepared cartridge was observed to be approximately 19 kPa. Some commercially available cartridges with pre-coated DNPH have a lower pressure drop, allowing the use of battery-operated pumps for sampling in the breathing zone. 6.1.2. Air sampling pump providing accurate and precise flow rates in the range of 1.0-1.5 l/min. 6.1.3. Flow regulator, flow meter, flow controller or similar device for measuring and controlling air flow through a sampling cartridge in the range of 0.50 - 1.20 l/min. 6.1.4. A flow calibrator, such as a rotameter, a soap-bubble flowmeter, or a liquid-sealed drum gas meter. 6.2. Sample preparation 6.2.1. Cartridge containers, borosilicate glass tubes (20 to 125 mm long) with polypropylene screw caps or other containers suitable for transporting loaded cartridges. 6.2.2. Polyethylene gloves for handling silica gel cartridges. 6.2.3. Shipping containers, metal boxes (4 L capacity) with a sealed lid, or other suitable containers with bubble wrap or other suitable padding to secure and cushion the impact of sealed cartridge containers. Note - To store cartridges with samples, use a heat-sealed plastic bag with foil layers, supplied complete with commercially available cartridges coated with DNPG. 6.2.4. Device for applying DNPH to cartridges. The syringe stand is an aluminum plate (dimensions 0.16 × 36 × 53 cm) with four adjustable legs. A plate with round holes (number of holes - 5 × 9), the diameter of which is slightly larger than the diameter of 10 ml syringes, symmetrically located from the center of the plate, allows for cleaning, application of DNPH and / or elution of sample for 45 cartridges (see Figure 3) .

a - device for applying DNPH; b - device for drying cartridges; 1_ glass syringe with a capacity of 10 ml; 2 - syringe stand; 3 - cartridges; 4 - drain glass; 5 - flow N 2; 6 - fitting for syringes; 7 - waste cup

Figure 3 - Devices for applying DNPH and drying sampling cartridges

6.2.5. A device for drying cartridges with gas injection devices and numerous fittings for standard syringes (see Figure 3). Note - The equipment specified in 6.2.4 and 6.2.5 is necessary only if the user independently produces cartridges with applied DNPH 6.3. Sample analysis 6.3.1. The HPLC system consists of a mobile phase vessel, a high pressure pump, an injection stopcock (automatic dispenser with a 25 µL loop volume or other suitable loop volume), a C-18 reverse phase column (e.g. 25 cm long, 4.6 i.d. mm, filler particle size 5 µm), a UV detector or a diode array detector operating at a wavelength of 360 nm, a data processing system or an electrical measuring recorder. DNPH derivative of formaldehyde is determined by reverse phase HPLC in isocratic eluent supply mode based on readings from a UV absorption detector operating at a wavelength of 360 nm. Blank cartridges are desorbed and analyzed in a similar manner. Formaldehyde and other carbonyl compounds in the sample are identified and quantified by comparing their retention times and peak heights or areas obtained from sample analysis and analysis of calibration solutions. NOTE Most commercially available HPLC analytical systems are suitable for this purpose. 6.3.2 Syringes and pipettes 6.3.2.1. HPLC injection syringes with a capacity of at least four times the volume of the loop (see 6.3.1). 6.3.2.2. Syringes with a capacity of 10 ml, used for applying DNPH to cartridges (polypropylene syringes can be used). 6.3.2.3. Fittings and plugs used to connect cartridges to the sampling system and to close prepared cartridges. 6.3.2.4. An automatic pipette dispenser operating on the principle of positive displacement, multiple dosing with a variable volume in the range from 0 to 10 ml (hereinafter referred to as a pipette dispenser).

7. Reagents

7.1. DNPH, before use recrystallized at least twice from acetonitrile, pure in the UV region of the spectrum. 7.2. Acetonitrile, pure in the UV region of the spectrum (each portion of the solvent must be tested before use). 7.3. Perchloric acid, solution with a mass fraction of 60%, ρ = 1.51 kg/l. 7.4. Hydrochloric acid, solution with a mass fraction from 36.5% to 38%, ρ = 1.19 kg/l. 7.5. Formaldehyde (formalin), solution with a mass fraction of 37%. 7.6. Aldehydes and ketones, high purity, used for the preparation of calibration samples of DNPH derivatives (optional). 7.7. Ethanol or methanol for chromatography. 7.8. High purity nitrogen. 7.9. Wood granulated charcoal (highest quality). 7.10. High purity (highest quality) helium.

8. Preparation of reagents and cartridges

8.1. Purification of 2,4-dinitrophenylhydrazine

The problem of DNPH contamination with formaldehyde is encountered quite often. DNPH is purified by repeated recrystallization from acetonitrile, pure in the UV region of the spectrum. Recrystallization is carried out at temperatures from 40°C to 60°C by slowly evaporating the solvent to obtain crystals of maximum size. The content of carbonyl compound impurities in DNPG, which is determined before analysis by HPLC, should not exceed 0.15 μg per cartridge and per individual compound. A supersaturated solution of DNPH is prepared by boiling a solution containing excess DNPH in 200 ml of acetonitrile for approximately 1 hour. The supernatant is then separated and poured into a beaker with a lid placed on a hot plate and gradually cooled to 40°C-60°C. . Maintain the solution at this temperature (40°C) until 95% of the solvent volume has evaporated. The solution is filtered, and the remaining crystals are washed twice with acetonitrile in a volume exceeding three times the apparent volume of the crystals. The crystals are transferred to another clean beaker, 200 ml of acetonitrile are added, heated to boiling, and the crystals are allowed to grow again while cooling to a temperature of 40°C-60°C until 95% of the solvent volume has evaporated. Repeat the process of washing the crystals. Take an aliquot of the solution and dilute tenfold with acetonitrile, then acidify with 1 ml of perchloric acid (3.8 mol/l) per 100 ml of DNPH solution and analyze by HPLC in accordance with 9.3.4. Warning - Cleaning of DNPG must be carried out with ventilation turned on and mandatory use of explosion protection equipment (screen). Note - The acid is necessary to catalyze the reaction of carbonyl compounds with DNPH. For these purposes, the strongest inorganic acids are used, such as perchloric, sulfuric, phosphoric or hydrochloric. In rare cases, the use of hydrochloric and sulfuric acids can lead to adverse effects. The level of formaldehyde hydrazone impurities in recrystallized DNPH is considered acceptable if the mass concentration is less than 0.025 μg/ml or the mass fraction of impurities in DNPH is less than 0.02%. If the level of impurities is unacceptable for specific sampling conditions, then recrystallization is repeated. The purified crystals are transferred to a glass flask, 200 ml of acetonitrile are added, capped, shaken slightly and allowed to stand for 12 hours. The supernatant liquid is analyzed on a chromatograph using the HPLC method in accordance with 9. 3.4. If the level of impurities is unacceptable, then pipet the entire supernatant solution, then add 25 ml of acetonitrile to the remaining purified crystals. Repeat washing the crystals with acetonitrile in 20 ml portions; After each addition of acetonitrile, the resulting supernatant is analyzed by HPLC until an acceptable level of impurities in the supernatant is confirmed. If the impurity level is acceptable, add 25 ml of acetonitrile, stopper the flask, shake and reserve for further use. The resulting saturated solution over the purified crystals is the main source solution of DNPH. Retains the minimum volume of saturated solution required for daily use, minimizing the loss of purified reagent when it is necessary to re-rinse the crystals to reduce impurity levels when more stringent purity requirements are imposed. The volume of the main initial saturated solution of DNPH required for analysis is taken with a clean pipette. Do not pour the original solution directly from the flask.

8.2. Preparation of DNPH-derived formaldehyde

A sufficient amount of hydrochloric acid (2 mol/L) is added to a portion of the recrystallized DNPH to obtain an almost saturated solution. Formaldehyde (formalin) is added to this solution in a molar excess relative to DNPH. Filter the precipitate of DNPH-formaldehyde derivative, wash it with hydrochloric acid (2 mol/l) and water and leave in air until dry. The purity of DNPH-derived formaldehyde is checked by determining its melting point (from 165°C to 166°C) or by HPLC analysis. If the impurity level is unacceptable, the derivative is recrystallized from ethanol. Repeat the purity check and recrystallization until an acceptable level of purity is achieved (for example, 99% mass fraction of the main component). DNPH-formaldehyde derivative is stored refrigerated (at a temperature of 4°C) in a place protected from light. It should be stable for at least 6 months. Storage in a nitrogen or argon atmosphere extends the shelf life of the DNPH derivative. The melting point temperatures of DNPH derivatives of some carbonyl compounds are given in Appendix B. DNPH derivatives of formaldehyde and other carbonyl compounds, used as standard samples, are commercially produced both in the form of pure crystals and in the form of individual or mixed initial solutions in acetonitrile.

8.3. Preparation of stock solutions of DNPH-formaldehyde derivative

A stock solution of DNPH-derived formaldehyde is prepared by dissolving a precisely known amount of the derivative in acetonitrile. A working calibration solution is prepared from the initial solution. The content of DNPH-derivative formaldehyde in calibration solutions should correspond to the expected range of its mass concentration in real samples. Stock solutions with a mass concentration of approximately 100 mg/l can be prepared by dissolving 10 mg of the solid derivative in 100 ml of acetonitrile. These solutions are used to prepare calibration solutions containing the corresponding derivatives in the mass concentration range from 0.5 to 20 μg/ml. All standard solutions are stored protected from light in hermetically sealed containers in the refrigerator. Before use, the solutions are kept at room temperature until thermal equilibrium is achieved. After four weeks, the solutions must be replaced with fresh ones.

8.4. Preparation of cartridges with DNPH applied to silica gel

8.4.1. General provisions The procedure is carried out in a laboratory with a very low content of aldehydes in the air. All glass and plastic laboratory glassware are thoroughly cleaned and rinsed in deionized water and aldehyde-free acetonitrile. Contact of reagents with air in the laboratory should be minimal. When working with cartridges, you should wear plastic gloves. 8.4.2. Solution for applying DNPH Using a pipette, add 30 ml of a saturated stock solution of DNPH into a 1000 ml volumetric flask, add 500 ml of acetonitrile and acidify with 1.0 ml of concentrated hydrochloric acid. The air above the acidified solution is filtered through a silica gel cartridge coated with DNPH to minimize the introduction of contamination from the laboratory air into the solution. The flask is shaken, then the solution is brought to the mark with acetonitrile. The flask is closed, inverted, and shaken several times until the solution becomes homogeneous. Transfer the acidified solution into a pipette dispenser with a scale from 0 to 10 ml. From the dispenser, slowly pour 10 to 20 ml of solution into a drain cup. Inject an aliquot of the solution into the vial and check the level of impurities in the acidified solution using HPLC in accordance with 9.3.4. The mass concentration of formaldehyde in the solution should be no more than 0.025 μg/ml. 8.4.3. Application of DNPG to silica gel in a cartridge The cartridge is removed from the packaging, the short end of the cartridge is connected to a syringe with a capacity of 10 ml, which is placed in the device for applying DNPG as shown in Figure 3a). Using a pipette dispenser, 10 ml of acetonitrile is injected into each syringe. The liquid should drain by gravity. Air bubbles that appear between the syringe and the silica gel cartridge are removed using acetonitrile from the syringe. Set up a pipette dispenser containing an acidified solution for applying DNPH to inject 7 ml into each cartridge. As soon as the flow of acetonitrile at the outlet of the cartridge stops, add 7 ml of solution for applying DNPH to each syringe. The solution for applying DNPH flows through the cartridge by gravity until the flow at the other end of the cartridge stops. Excess liquid at the outlet of each cartridge is removed using filter paper. Assemble the device for drying cartridges (see Figure 3 b). A pre-prepared cartridge with DNPG applied (for example, a scrubber or “protective” cartridge) is installed at each outlet. These "safety" cartridges are designed to remove traces of formaldehyde that may be present in the nitrogen supply. They are prepared by drying a few re-impregnated cartridges according to the instructions below and used to keep the remaining cartridges clean. Install the cartridge adapter (expanded into a cone at both ends, with an outer diameter of 0.64 to 2.5 cm, made of fluorocarbon tube, with an inner diameter slightly smaller than the outer diameter of the cartridge inlet) onto the long end of the “protective” cartridge. Disconnect the cartridges from the syringes and connect the short ends of the cartridges to the free ends of the adapters already attached to the “protective” cartridges. Nitrogen is passed through each cartridge at a flow rate of 300 - 400 ml/min. Wash the outer surfaces and outlet ends of the cartridges with acetonitrile using a Pasteur pipette. After 15 minutes, the nitrogen supply is stopped, the remaining acetonitrile is removed from the outer surfaces of the cartridges, and the dried cartridges are disconnected. Both ends of the loaded cartridges are sealed with standard polypropylene syringe caps and the capped cartridges are placed in borosilicate glass tubes with polypropylene screw caps. Each individual glass cartridge storage container is marked with a batch and batch number and the entire batch is stored in the refrigerator until use. It has been established that the contents of loaded cartridges remain stable for at least 6 months. when stored at a temperature of 4°C in a place protected from light.

9. Methodology

9.1. Sample selection

Assemble the sampling system and ensure that the pump provides a constant flow rate throughout the sampling period. Loaded cartridges may retain their sampling characteristics if the ambient temperature is above 10°C. If necessary, install an ozone scrubber or trap (see 4.2). Before starting sampling, check the tightness of the system. Close the inlet (short) end of the cartridge so that there is no air flow at the pump outlet. In this case, the flow meter should not record the air flow through the sampling system. During unattended or extended sampling periods, it is recommended to use a flow regulator or pump with flow compensation when sampling in the breathing zone to maintain constant air flow. The flow regulator is adjusted so that the flow value is at least 20% lower than the set maximum air flow through the cartridge. Note - The silica gel in the cartridge is held between two fine porous filters. Air flow may vary during sampling due to aerosol particles settling on the front filter. The change in flow can be significant when sampling air containing large amounts of suspended particles. Install the sampling system (including the blank cartridge) and check the air flow rate at a value close to expected. Typically, air flow is set in the range of 0.5 - 1.2 l/min. The total number of moles of carbonyl compounds in the volume of sampled air should not exceed the amount of DNPH in the cartridge (2 mg or 0.01 mol; 1 to 2 mg when using commercially available preloaded cartridges). Typically, the estimated mass of the analyte in the sample should be less than 75% of the mass of DNPG loaded in the cartridge [100 to 200 μg for HCHO, including interfering substances (see Section 4)]. Calibration is carried out using a soap-foam bubble flow meter or a drum gas meter with a liquid seal connected to the flow outlet, provided that the system is sealed. Note - A calibration method that does not require tightness of the system after the pump is given in [13]. To determine the sample volume, record and record the flow rate at the beginning and end of the sampling period. If the sampling period is more than 2 hours, then the flow rate is measured several times during sampling. To monitor flow without interfering with the sampling process, a rotameter is installed in the system. It is also possible to use a sampling pump with direct measurement and continuous recording of flow values. Before sampling begins, the loaded cartridge is removed from a sealed metal or other suitable shipping container. Before connecting to a flow stimulator (aspirator, pump), the cartridge is kept at room temperature until thermal equilibrium is achieved, without removing it from the glass container. Commercially available pre-loaded cartridges are subjected to the same procedure. Wearing plastic gloves, remove the cartridge plug and connect it to the flow stimulator using an adapter. The cartridge is connected so that its short end is the inlet end for the sample. Connection of commercially available cartridges with pre-applied DNPH is carried out in accordance with the manufacturer's instructions. Some commercially available cartridges are sealed glass tubes. In this case, it is necessary to break off the ends of the tube using a glass cutter first. Connect the end of the cartridge with a smaller amount of sorbent to the sampling line so that a larger amount of sorbent is at the air sample inlet. Use caution when handling broken ends of the tube. Turn on the pump and set the required flow rate. Typically, the flow rate through one cartridge is 1.0 l/min, and in the case of two cartridges connected in series, it is 0.8 l/min. Sampling is carried out over a set period of time, while the values ​​of sampling parameters are periodically recorded. If the ambient temperature during sampling is below 10°C, ensure that the sampling cartridge is at a higher temperature. When sampling was carried out in different weather conditions - in the cold, wet and dry winter months, in the hot and humid summer months - there was no significant effect of relative air humidity on the sampling results. At the end of sampling, turn off the pump. Immediately before turning it off, check the air flow. If the air flow values ​​at the beginning and end of the sampling period differ by more than 15%, then the sample is marked as doubtful. Immediately after sampling, remove the cartridge from the sampling system (wearing plastic gloves), cap it, and place it back into the labeled container. Seal the container with fluoroplastic tape and place it in a metal container containing a layer of granulated charcoal 2 to 5 cm thick, or in another suitable container with an absorbent. If necessary, a heat-sealed plastic bag with foil layers is used to store the sample cartridge. Before analysis, the sample cartridge is stored in the refrigerator. The storage time of the cartridge in the refrigerator should not exceed 30 days. If the sample must be transported to an analytical laboratory for analysis, the storage time of the sample cartridge without refrigeration should be kept to a minimum and not exceed two days. The average sampling flow rate q A, ml/min, is calculated using the formula

q A = / n , (1)

Where q 1, q 2, … q n are the flow rates at the beginning, intermediate points and end of sampling; n- number of averaging points. The total volume of air V m , l, selected at a known temperature and pressure during the sampling process, is calculated using the formula

V m = (T 2 - T 1) q A /1000, (2)

Where T 2 - end time of sampling; T 1 - start time of sampling; T 2 - T 1 - sampling duration, min; q A - average flow rate, ml/min.

9.2. Blank samples

For each sample series, at least one blank sample obtained under the sampling conditions must be analyzed. If a series includes 10 - 20 samples, then the number of blank samples must be at least 10% of the total number of samples. To determine the required number of blank samples, the total number of samples within a series or time interval should be recorded. At the sampling site, blank sample cartridges are treated in the same way as real sample cartridges, except for the sampling process itself. Blank sampling shall comply with the requirements given in 9.1. It is also advisable to analyze blank cartridges left in the laboratory to distinguish between contamination that may have been introduced at the sampling site and in the laboratory.

9.3. Sample analysis

9.3.1. Sample preparation Samples are transported to the laboratory in a suitable container containing a layer of granulated charcoal 2 to 5 cm thick and stored in a refrigerator until analysis. Samples can also be stored in individual containers. The time interval between sampling and analysis should be no more than 30 days. 9.3.2. Desorption of samples The sample cartridge with the short end (inlet) is connected to a clean syringe. To prevent insoluble particles from entering the eluate, the direction of liquid flow during desorption must coincide with the direction of air flow during sampling. If the eluate is filtered before HPLC analysis, reverse desorption can be performed. For each batch of samples, the filtered clean extract is analyzed to ensure that the filter is free of contaminants. The syringe with the attached cartridge is placed on the syringe rack. Desorption of DNPH-derivatives of carbonyl compounds and unreacted DNPH is carried out by allowing 5 ml of acetonitrile to flow from the syringe by gravity through the cartridge into a graduated test tube or volumetric flask with a capacity of 5 ml. Depending on the sampling cartridge used, other volumes of acetonitrile may be injected. Note - The free volume of a dry silica gel cartridge is slightly more than 1 ml. The eluate flow may stop before all the acetonitrile has flowed from the syringe into the cartridge due to the presence of air bubbles between the cartridge filter and the syringe. In this case, air bubbles are removed by introducing acetonitrile into the syringe using a long Pasteur pipette. The solution is diluted with acetonitrile to the 5 ml mark. The flask is labeled in the same way as the sample. An aliquot is pipetted into a vial with a fluorocarbon membrane. An aliquot is analyzed for the content of DNPH-derived carbonyl compounds by HPLC. As a backup, a second aliquot can be taken and stored in the refrigerator until the analysis is completed and suitable analysis results are obtained from the first aliquot. If necessary, a second aliquot is used for confirmatory analysis. When using sealed glass tubes containing two layers of sorbent coated with DNPG for sampling, break off the end of the tube located closer to the second layer of sorbent (outlet end). Carefully remove the spring and glass wool plug holding the sorbent layer. Pour the sorbent into a clean 4 ml glass vial with a fluorocarbon membrane or lid. The vial is marked as a reserve part of the sample. Carefully remove the second glass wool plug and pour the remaining sorbent into another 4 ml vial. The vial is labeled as the main part of the sample. Add 3 ml of acetonitrile to each vial with a pipette, close the vials and leave for 30 minutes, during which the vials are shaken periodically. 9.3.3. HPLC calibration Calibration solutions are prepared by dissolving the DNPH derivative of formaldehyde (8.3) in acetonitrile. Prepare individual stock solutions with a mass concentration of 100 mg/l by dissolving 10 mg of the solid derivative in 100 ml of the mobile phase. Each calibration solution is analyzed twice (at least five different mass concentration values) and a table is drawn up depending on the values ​​of the output signals corresponding to the area of ​​the chromatographic peaks on the introduced mass of the corresponding substance (or, more conveniently, on the introduced mass of DNPH-derivative formaldehyde at fixed loop volume (see Figures 4 and 5)). During the calibration process, operations are performed corresponding to the operations carried out during sample analysis and established in 9.3.4. To avoid the chromatograph memory effect, the analysis begins with a solution with the lowest mass concentration. When using a UV detector or a diode array detector, a linear dependence of the output signal should be obtained when introducing solutions with a mass concentration in the range of 0.05 - 20 μg/ml with an injected volume of 25 μl. The results obtained are used to construct a calibration graph (see Figure 6). The calibration characteristic (the dependence of the output signal corresponding to the peak area on the mass concentration value), obtained by the least squares method, is considered linear if the correlation coefficient is at least 0.999. The retention times for each analyte should not differ from each other by more than 2%. After establishing a linear calibration characteristic, its stability is checked daily using a calibration solution with a mass concentration value close to the expected value of each component, but not less than 10 times the detection limit. The relative change in output signal determined during daily testing should not exceed 10% for analytes with a mass concentration of at least 1 µg/ml and 20% for analytes with a mass concentration of approximately 0.5 µg/ml. If a larger change is observed, it is necessary to re-calibrate or construct a new calibration graph based on freshly prepared calibration solutions.

Chromatography conditions: column: C-18 reverse phase; mobile phase: with a volume ratio of 60% acetonitrile/40% water; detector: UV detector operating at a wavelength of 360 nm; flow rate: 1 ml/min; retention time: for DNPH-formaldehyde derivative approximately 7 minutes; volume of injected sample: 25 µl.

Figure 4 - Example of a chromatogram of DNPH - a formaldehyde derivative

Chromatography conditions: column: C-18 reverse phase; mobile phase: with a volume ratio of 60% acetonitrile/40% water; detector: UV detector operating at a wavelength of 360 nm; flow rate: 1 ml/min; retention time: for DNPH-formaldehyde derivative approximately 7 minutes; volume of injected sample: 25 µl.

Figure 5 - Examples of chromatograms of DNPH-derivative of formaldehyde at its various mass concentrations

Chromatography conditions: correlation coefficient: 0.9999; Column: C-18 reverse phase; mobile phase: with a volume ratio of 60% acetonitrile/40% water; detector: UV detector operating at a wavelength of 360 nm; flow rate: 1 ml/min; retention time: for DNPH-formaldehyde derivative approximately 7 minutes; volume of injected sample: 25 µl;

Figure 6 - Example of a calibration graph for formaldehyde

9.3.4. Formaldehyde Analysis by HPLC Assemble and calibrate the HPLC system in accordance with 9.3.3, with a typical system being: Column: C-18, 4.6 mm i.d., 25 cm long, or equivalent; it is not necessary to control the column temperature; mobile phase: 60% acetonitrile/40% water (volume ratio), isocratic; detector: UV detector operating at a wavelength of 360 nm; flow rate: 1.0 ml/min; retention time: for DNPH-formaldehyde derivative 7 min - using one C-18 column, 3 min - using two C-18 columns; volume of injected sample: 25 µl. Before each analysis, the detector baseline is checked to ensure stable conditions. Prepare the mobile phase for HPLC by mixing 600 ml of acetonitrile and 400 ml of water, or set the appropriate parameters for gradient elution. The resulting mixture is filtered through a polyester membrane filter with a pore size of 0.22 μm in a vacuum filtration device made only of glass or fluoroplastic. Degas the filtered mobile phase by purging with helium for 10 to 15 minutes (100 ml/min) or by heating to 60°C for 5 to 10 minutes in a laboratory conical flask covered with a watch glass. To prevent the formation of gas bubbles in the detector cell, a constant resistance limiter (350 kPa) or a short (15 - 30 cm) fluoroplastic tube with an internal diameter of 0.25 mm is installed after it. The mobile phase is poured into the solvent container and the flow rate is set to 1.0 ml/min. Before the first analysis, the pump should run for 20 - 30 minutes. The detector is turned on at least 30 minutes before the start of the first analysis. The output signal of the detector is recorded using an electrical recording instrument or similar output device. For systems with manual sample injection, draw at least 100 µl of sample into a clean injection syringe for injection into the chromatograph. Fill the dosing tap loop with the mobile phase (the dosing tap must be set to the “loading” position), adding excess sample using a syringe. To start chromatography, the dispenser tap is moved to the “sample injection” position. Simultaneously with the input, the data processing system is activated, the input point is turned on and marked on the chart tape of the electrical measuring recorder. After approximately 1 minute, move the dispenser tap from the “sample input” position to the “loading” position, rinse or wash the syringe and dosing loop with a mixture of acetonitrile and water to prepare for the analysis of the next sample. It is not allowed to introduce solvent into the loop of the dosing tap when the tap is in the “sample input” position. Once the DNPH-derived formaldehyde has eluted (see Figure 4), stop recording and calculate the mass concentration of the components in accordance with Section 10. The system can be used for further sample analysis once a stable baseline has been achieved. Note - After several analyses, contamination of the column (as evidenced, for example, by an increase in pressure with each subsequent sample injection at a given flow rate and solvent composition) can be eliminated by washing it with 100% acetonitrile in a volume several times greater than the volume of the column. Similar protection can be achieved using precolumns. If the mass concentration of the analyte goes beyond the linear portion of the calibration characteristic of the system, the sample is diluted with the mobile phase or a smaller volume of sample is introduced into the chromatograph. If the retention time obtained from previous injections is not reproducible (maximum permissible deviation ± 10%), then the acetonitrile-water ratio can be increased or decreased to obtain the appropriate retention time. If the retention time is too long, the ratio is increased; if too little, the ratio is reduced. If it is necessary to replace the solvent, re-calibrate before introducing the sample (see 9.3.3). Note - The given chromatographic conditions should be optimized for the determination of formaldehyde. It is recommended that the analyst conduct studies with an existing HPLC system to optimize chromatographic conditions for a particular analytical problem. HPLC systems with automatic sample injection and data acquisition can also be used. The resulting chromatogram is examined for ozone interference in accordance with 4.2 and Figure 2. 9.3.5 Analysis of other aldehydes and ketones by HPLC 9.3.5.1. General provisions Optimization of chromatographic conditions through the use of two C-18 columns connected in series and a gradient eluent supply allows the analysis of other aldehydes and ketones taken from air. In particular, chromatography conditions are optimized to separate acetone, propionaldehyde and some other higher molecular weight aldehydes in an analysis time of approximately 1 hour. The composition of the mobile phase is periodically changed using a linear gradient program to obtain maximum separation of C3, C4 and benzaldehyde in the corresponding region of the chromatogram . For this purpose, the following gradient program has been developed: at the moment of sample injection, the volume ratio of solutions is changed from 60% acetonitrile/40% water to 75% acetonitrile/25% water for 36 minutes; up to 100% acetonitrile - within 20 minutes; 100% acetonitrile - for 5 minutes; change the direction of linear gradient programming from 100% acetonitrile to 60% acetonitrile/40% water for 1 min; maintain a volume ratio of 60% acetonitrile/40% water for 15 min. 9.3.5.2. Analysis of samples for other carbonyl compounds Assemble and calibrate the HPLC system in accordance with 9.3.3. Typical systems would be: column: two C-18 columns connected in series; mobile phase: acetonitrile/water; linear gradient mode; detector: UV detector operating at a wavelength of 360 nm; flow rate: 1.0 ml/min; gradient program: according to 9.3.4. The chromatography conditions given above have been optimized for HPLC gradient systems with a UV or diode array detector, an autosampler with a 25 μL dosing loop volume, two C-18 columns (4.6 × 250 mm) and an electrical recorder or electronic integrator. It is recommended that the analyst conduct studies on an existing HPLC system to optimize chromatographic conditions for a specific analytical problem. Optimization is required at least for the separation of acrolein, acetone and propionaldehyde. NOTE: Column manufacturers usually provide recommendations for optimal separation conditions for DNPH derivatives for reverse phase columns. These recommendations can eliminate the need for two columns without compromising the separation of carbonyl compounds. Carbonyl compounds in the sample are determined qualitatively and quantitatively by comparing their retention time and peak area with similar indicators for reference samples of DNPH derivatives. Formaldehyde, acetaldehyde, acetone, propionaldehyde, cretonaldehyde, benzaldehyde and o-, m-, p-toluyl aldehydes are determined with a high degree of reliability. The determination of butyraldehyde is less reliable due to its co-elution with isobutyraldehyde and methyl ethyl ketone under the chromatographic conditions specified above. A typical chromatogram obtained with a gradient elution HPLC system is shown in Figure 7. The mass concentration of individual carbonyl compounds is determined according to 9.3.4.

Peak identification

Compound

Mass concentration, µg/ml

Formaldehyde

Acetaldehyde

Acrolein

Acetone

Propionic aldehyde

Crotonaldehyde

Butyraldehyde

Benzaldehyde

Isovaleraldehyde

Valeraldehyde

o - Toluylaldehyde

m - Toluylaldehyde

l - Toluylaldehyde

Hexanal

2, 5-D and methyl benzaldehyde

Figure 7 - Example of chromatographic separation of DNPH - derivatives of 15 carbonyl compounds

10. Calculation of measurement results

The total mass of the analyte (DNPH derivative) for each sample is calculated using the formula

m d = m s - m b , (3)

Where m d is the adjusted mass of DNPH derivative extracted from the cartridge, μg; m s is the uncorrected mass of the sample cartridge, µg:

m s = A s ( c std/ A std) V s d s; (4)

m b is the mass of the analyte in the cartridge with a blank sample, µg:

m b = A b( c std/ A std) V b d b ; (5)

A s is the peak area of ​​the analyte eluted from the sample cartridge, arbitrary units; A b is the peak area of ​​the analyte eluted from the cartridge with a blank sample, arbitrary units; A std is the peak area of ​​the analyte in the calibration solution for daily calibration, arbitrary units; c std - mass concentration of the analyte in the calibration solution for daily calibration, m kg / ml; V s is the total volume of eluate obtained for the sample cartridge, ml; V b - total volume of eluate obtained for the cartridge with a blank sample, ml; d s - dilution factor of the sample eluate: 1, if the sample was not re-diluted; V d/ V a if the sample was diluted so that the output signal was in the linearity region of the detector, where V d - volume after dilution, ml; V a - aliquot used for dilution, ml; d b is the dilution factor of the blank sample, equal to 1.0. The mass concentration of a carbonyl compound with A, ng/l, in a sample is calculated using the formula

c A = m d ( M c/ M der)1000/ V m , (6)

Where M c is the molecular weight of the carbonyl compound (for formaldehyde it is 30); M der is the molecular weight of the DNPH derivative (for formaldehyde it is 210); V m - total volume of indoor air sample, selected according to 9.1, l. Note - Parts per billion and parts per million are not recommended. However, for the convenience of some users, the volume ratio of carbonyl compound ca in parts per billion (ppb) is calculated using the formula

c A= c As ∙ 24.4/ M c , (7)

The total volume of air sample V s, l, reduced to a temperature of 25 ° C and a pressure of 101.3 kPa, is calculated using the formula

V s = (( V m ρ A)/101.3)(298/(273 + T A)), (8)

Where ρ A - average atmospheric pressure inside a closed room, kPa; T A - average ambient temperature in a closed room, °C. If it is necessary to express the analyte content in parts per million (ppm) under standard environmental conditions (temperature 25°C and pressure 101.3 kPa) for comparison with reference samples whose composition is established in the same values, the sampled volume should not be reduced to standard conditions.

11. Performance criteria and quality control of measurement results

11.1. General provisions

This section sets out the measures necessary to ensure quality control of measurement results and guidance on meeting the performance criteria that must be met. The user of the standard must comply with the requirements of ISO 9001, ISO 17025.

11.2. Standard Operating Procedures

The user of the standard should develop standard operating procedures for the following laboratory activities: assembly, calibration and operation of the sampling system, specifying the manufacturer and model of equipment used; preparation, cleaning, storage and processing of reagents used in sampling and the samples themselves; assembly, calibration and use of the HPLC system, indicating the brand and model of equipment used; a method of recording and processing data indicating the computer hardware and software used. Descriptions of standard operating procedures should include step-by-step instructions and be accessible and understandable to personnel working in the laboratory. Standard operating procedures shall comply with the requirements of this standard.

11.3. HPLC System Efficiency

The efficiency of an HPLC system is determined by the column efficiency η (number of theoretical plates), which is calculated using the formula

η = 5.54( t r /w 1/2) 2 , (9)

Where t r - analyte retention time, s; w 1/2 - peak width for one component at half height, s. The column efficiency must be at least 5000 theoretical plates. The relative standard deviation of the output signal during repeated daily injections of samples into the HPLC system should not be more than ±10% for calibration solutions with an analyte mass concentration of at least 1 μg/ml. With a mass concentration of some carbonyl compounds of no more than 0.5 μg/ml, the precision of repeated analyzes can increase to 20%. Retention time precision should be within ±7% on any given day of analysis.

11.4. Sample loss

Sample loss occurs when the load capacity of the sorbent is exceeded or when the volumetric flow rate exceeds the maximum allowable for the sampling system being used. Sample loss can be prevented by installing two sample cartridges in series and then analyzing the contents of each, or by installing a two-section sorbent cartridge and then analyzing both sections. If the amount of analyte in the reserve section is more than 15% of the amount of analyte in the main section, a “breakthrough” is assumed and the accuracy of the results is questioned.

12. Precision and uncertainty

Just as in the analysis of other compounds, the precision and uncertainty of the result of determining the formaldehyde content in indoor air is influenced by two factors: the reproducibility of the analytical procedure and the change in the analyte content in the air over time. The latter factor is thought to have a much greater influence than the former, although it is difficult to quantify the effect of varying source intensity and ventilation conditions. General information about the uncertainty values ​​associated with the analytical procedure is given in Appendix A.

Appendix A
(informative)
Precision and uncertainty

A procedure similar to the analytical procedure given in this standard was evaluated. The precision related to the analytical procedure should be within ± 10% at an analyte mass concentration of at least 1 µg/ml. At a mass concentration of no more than 0.5 μg/ml, the precision for repeated analyzes of some carbonyl compounds can increase to 25%. In a round robin test [14] - [16], a method using silica gel cartridges (55 to 105 µm particle size) coated with DNPH, similar to the method specified in this standard, was evaluated. The results of the assessment given below can be used to evaluate the effectiveness of using this method for analyzing indoor air. Two different laboratories used the cartridges to make more than 1,500 measurements of formaldehyde and other carbonyl compounds in ambient air as part of a research program conducted in 14 cities in the United States [15], [16]. The precision of 45 repeated injections of a formaldehyde derivative DNPH calibration solution into the HPLC system over 2 months, expressed as relative standard deviation, was 0.85%. Based on the results of triplicate analysis of each of 12 identical samples from cartridges coated with DNPH, formaldehyde content values ​​were obtained that were consistent within a relative standard deviation of 10.9%. 16 laboratories in the USA, Canada and Europe also took part in the round-robin testing. During these tests, an analysis was carried out of 250 cartridges with blank samples, three sets of 30 cartridges each with the content values ​​of introduced DNPH derivatives and 13 series of cartridges exposed in an environment with vehicle exhaust gases [14] - [16]. Cartridges meeting the requirements of 4.2 were prepared by a single laboratory. All samples were randomly distributed among laboratories participating in the round-robin trial. The results of the circular tests are summarized and shown in Table A.1. NOTE: No standardized HPLC analytical procedure was used during the round robin testing. Test participants used HPLC-based techniques that they use in practice in their laboratories. The absolute value of the difference, expressed as a percentage, between the results of two series of measurements (sampling from the same place) carried out under the US research program in 1988 was 11.8% for formaldehyde (n = 405), acetaldehyde - 14 .5% (n = 386) and acetone - 16.7% (n = 346) [15], [16]. As a result of the analysis of two samples taken at almost the same point within the framework of this program for formaldehyde content by another laboratory, the relative standard deviation was 0.07, the correlation coefficient was 0.98, and the uncertainty was minus 0.05 for formaldehyde [15]. The corresponding values ​​for acetaldehyde were 0.12; 0.95 and minus 0.50, and for acetone - 0.15; 0.95 and minus 0.54 [16]. A one-year analysis of DNPH cartridges by one laboratory showed mean uncertainty of 6.2% for formaldehyde (n = 14) and 13.8% for acetaldehyde (n = 13). Analysis of 30 DNPH cartridges by one laboratory as part of this program showed that the average uncertainty was 1.0% (ranging from minus 49% to plus 28%) for formaldehyde and 5.1% (ranging from minus 38% to minus 39%) for acetaldehyde. Table A.1 - Results of circular tests

Sample type

Formaldehyde

Acetaldehyde

Propionic aldehyde

Benzaldehyde

Blank cartridges:

aldehyde, µg

rsd,%

n

Sample cartridge 3):

recovery rate, % (rsd, %)

short

average

high

n

Environmental samples with vehicle exhaust gases:

aldehyde, mg

rsd,%

n

a) Low, medium and high levels of aldehyde introduced into the cartridge were approximately 0.5; 5 and 10 mcg respectively. Note - 16 laboratories took part in the studies. The values ​​were obtained from the data series after removing outliers from the data series. Designations used in the table: rsd - relative standard deviation; n - number of measurements.

Appendix B
(informative)
Melting points of DNPH-derived carbonyl compounds

Table B.1 - Melting points of DNPH-derivatives of carbonyl compounds

Name of carbonyl compound

Melting point of DNPH derivative [17], °C

Acetaldehyde

From 152 to 153 (168.5[18], 168[19])

Acetone

From 125 to 127 (128[18], 128[19])

Benzaldehyde

240 to 242 (235[19])

Butyraldehyde

119 to 120 (122[19])

Cretonaldehyde

191 to 192 (190[19])

2,5-dimethylbenzaldehyde

From 216.5 to 219.5

Formaldehyde

166 (167 [ 18], 166 [ 19])

Hexanaldehyde

From 106 to 107

Isovaleraldehyde

From 121.5 to 123.5

Propionic aldehyde

144 to 145 (155[19])

o - Toluylaldehyde

193 to 194 (193 to 194 [19])

m - Toluylaldehyde

212 (212 [ 19])

n - Toluylaldehyde

234 to 236 (234[19])

Valeraldehyde

108 to 108.5 (98[19])

Appendix C
(informative)
Information on the compliance of national standards of the Russian Federation with reference international standards

Table C.1

Designation of the reference international standard

Designation and name of the corresponding national standard

ISO 9001:2000

GOST R ISO 9001-2001 Quality management systems. Requirements

ISO 16000-1:2004

GOST R ISO 16000-1-2007 Air of enclosed spaces. Part 1. Sampling. General provisions

ISO 16000-2:2004

GOST R ISO 16000-2-2007 Air of enclosed spaces. Part 2. Sampling for formaldehyde content. Basic provisions

ISO 16000-4:2004

GOST R ISO: 16000-4-2007 Air of enclosed spaces. Part 4. Determination of formaldehyde. Diffusion sampling method

ISO/IEC 17025:2005

GOST R ISO /IEC 17025-2006 General requirements for the competence of testing and calibration laboratories

*There is no corresponding national standard. Before its approval, it is recommended to use the Russian translation of this international standard. A translation of this international standard is located in the Federal Information Fund of Technical Regulations and Standards.

Bibliography

Method TO-11A, EPA-625/R-96-010b, Compendium of Methods for the Determination of Toxic Organic Compounds in Ambient Air, U.S. Environmental Protection Agency, Cincinnati, OH, 1996

Air Quality Guidelines for Europe. Copenhagen: WHO Regional Office for Europe. WHO Regional Publications. European series No. 23/1987

Revised values ​​see webpages:

www.who.int.peh, www.who.dk/envhlth/pdf/airqual.pdf

Tejada, S. V., Evaluation of pf silica gel cartridges coated in situ with acidified 2,4-dinitrophenylhydrazine for sampling aldehydes and ketones in air, Int. J. Environ. Anal. Chem., 26, 1986, pp. 167 - 185

Grosjean, D., Ambient levels of formaldehyde, acetaldehyde, and formic acid in southern California: Results of a one-year baseline study, Environ. Sci. Technol., 25, 1991, pp. 710 - 715

J.-O. Levin and R. Lindahl, Aldehyde measuring methods using DNPH-coated filters - Summary and conclusions, Proc. Workshop "Sampling Project", 27 - 28 June, 1996, Mol, Belgium

VDI 3862 Part 2

Gaseous Emission Measurement - Measurement of Aliphatic and Aromatic Aldehydes and Ketones - DNPH Method - Impinger Method

VDI 3862 Part 3

Gaseous Emission Measurement - Measurement of Aliphatic and Aromatic Aldehydes and Ketones - DNPH Method - Cartridges Method

A. Sirju and P.B. Shepson, Laboratory and field investigation of the DNPH cartridge technique for the measurement of atmospheric carbonyl compounds, Environ. Sci. Technol., 29, 1995, pp. 384 - 392

Arnts, R.R., and Tejada, S.V., 2,4-Dinitrophenylhydrazine-coated silica gel cartridge method for determination of formaldehyde in air: Identification of an ozone interference, Environ. Sci. Technol., 23, 1989, pp. 1428 - 1430

Sirju, A., and Shepson, P.B. Laboratory and field evaluation of the DNPH cartridge technique for the measurement of atmospheric carbonyl compounds, Environ. Sci. Technol., 29, 1995, pp. 384 - 392

R.G. Merrill, Jr., D-P. Dayton, P.L. O"Hara, and R.F. Jongleux, Effects of ozone removal on the measurement of carbonyl compounds in ambient air: Field experience using Method TO- 11, in Measurement of Toxic and Related Air Pollutants, Vol. 1, Air & Waste Management Association Publication VIP -21, Pittsburgh, PA, U.S.A., 1991, pp. 51 - 60

T.E. Kleindienst, E.W. Corse, F.T. Blanchard, and W.A. Lonneman, Evaluation of the performance of DNPH-coated silica gel and C1 8 cartridges in the measurement of formaldehyde in the presence and absence of ozone, Environ. Sci. Technol., 32, 1998, pp. 124 - 130

EN 1232:1997

Workplace atmospheres - Pumps for personal sampling of chemical agents - Requirements and test methods

ASTM D51 97-97 Standard Test Method for Determination of Formaldehyde and Other Carbonyl Compounds in Air (Active Sampler Methodology), Annual Book of ASTM Standards, 11.03, American Society for Testing and Materials, West Conshohoken, PA, U.S.A. , pp. 472 - 482

USEPA, 1989 Urban airtoxics monitoring program: Formaldehyde results, Report No. 450/4-91/006. U.S. Environmental Protection Agency, Research Triangle Park, NC, U.S.A., January 1991

USEPA, 1990 Urban Air Toxics Monitoring Program: Carbonyl Results, Report No. 450/4-91/025, U.S. Environmental Protection Agency, Research Triangle Park, NC, U.S.A., July 1991

Certificate of Analysis, Radian International, Austin, TX, U.S.A

Handbook of Chemistry and Physics, CRC, 18901 Cranwood Parkway, Cleveland, OH, U.S.A.

Organikum, Organisch-chemisches Grundpraktikum, Wiley-VCH, Weinheim, Germany

Key words: air, quality, confined space, formaldehyde, carbonyl compounds, sampling, sample analysis, high performance liquid chromatography method, ultraviolet detector

STATE COMMITTEE OF THE RUSSIAN FEDERATION
ENVIRONMENTAL PROTECTION

QUANTITATIVE CHEMICAL ANALYSIS OF WATER

MEASUREMENT PROCEDURE
MASS CONCENTRATION OF FORMALDEHYDE
IN SAMPLES OF NATURAL AND TREATED WASTEWATER
BY PHOTOMETRIC METHOD WITH ACETYLACETONE

If the mass concentration of formaldehyde in the analyzed sample exceeds the upper limit, then the sample may be diluted so that the concentration of formaldehyde corresponds to the regulated range.

The interfering influences of other sample components are eliminated during the process of distilling off formaldehyde with water vapor.

2. PRINCIPLE OF THE METHOD

The photometric method for determining the mass concentration of formaldehyde is based on the formation, in the presence of ammonium ions, of a yellow-colored reaction product of formaldehyde with acetylacetone. The color intensity of the resulting compound is proportional to the formaldehyde content in the sample. Optical density measurements are carried out at wavelength? = 412 nm.

3. ATTRIBUTED CHARACTERISTICS OF MEASUREMENT ERROR AND ITS COMPONENTS

This technique ensures that analysis results are obtained with an error not exceeding the values ​​given in Table 1.

Table 1

Measurement range, values ​​of accuracy, accuracy, repeatability, reproducibility indicators

The accuracy indicator values ​​of the method are used when:

Registration of analysis results issued by the laboratory;

Assessing the activities of laboratories for the quality of testing;

Assessing the possibility of using the analysis results when implementing the technique in a specific laboratory.

4. MEASURING INSTRUMENTS, AUXILIARY DEVICES, REAGENTS AND MATERIALS

4.1. Measuring instruments

Spectrophotometer or photometer that allows you to measure optical density at? = 412 nm
Cuvettes with an absorbing layer thickness of 50 mm
divisions 0.1 mg any type	GOST 24104-2001
General purpose laboratory scales with the largest weighing limit 200 g and the lowest price divisions 10 mg any type	GOST 24104-2001
CO with certified formaldehyde content with error no more than 1% at P = 0.95 (or formaldehyde, clause 4.3)
Volumetric flasks, filling flasks
Graduated pipettes
Single label pipettes
Measuring cylinders

4.2. Assistive devices

Electric hotplates with closed spiral and adjustable heating power
Laboratory drying cabinet with heating temperature up to 130 °C
Water bath
Household refrigerator
Weighing cups (bugs)
Chemical beakers
V-1-1000 THS
Laboratory funnels
Installations for the distillation of formaldehyde (round-bottom flasks K-1-250-29/32 THS with nozzle H1 or drop eliminator with outlet type KO, refrigerator with straight tube KhPT-1-300-14/23 THS, allonge AI 14/23 XS)
Conical flasks
Kn-2-100-18 THS
Kn-1-250-18-29/32 HS
Dropper 1(2)-50 HS
Glass rods 25 - 30 cm long and? 3 - 4 mm

Measuring instruments must be verified within the established time limits.

It is allowed to use other, including imported, measuring instruments and auxiliary devices with characteristics no worse than those given in paragraphs. 4.1 and 4.2.

4.3. Reagents and materials

Formaldehyde, 40% aqueous solution
Acetyl acetone, freshly distilled
Ammonia, aqueous, concentrated
Ammonium acetate
Sulfuric acid
Hydrochloric acid
Acetic acid
Potassium hydroxide or
sodium hydroxide
Potassium bichromate (potassium dichromate) or
potassium dichromate, standard titer 0.1 mol/dm 3 equivalents
Sodium thiosulfate (sodium sulfate), pentahydrate, or
sodium sulfate (thiosulfate), standard titer 0.1 mol/dm 3 equivalents
Potassium iodide
Crystalline iodine or
iodine, standard titer 0.01 mol/dm 3 equivalents
Anhydrous sodium sulfate Na 2 SO 4
Anhydrous sodium carbonate Na 2 CO 3
Chloroform
Soluble starch
Universal indicator paper
Ashless filters “white tape”
Distilled water

All reagents used for analysis must be of analytical grade. or reagent grade

It is allowed to use reagents manufactured according to other regulatory and technical documentation, including imported ones, with a qualification not lower than analytical grade.

6. REQUIREMENTS FOR OPERATOR QUALIFICATIONS

The measurements can be carried out by an analytical chemist who is proficient in the technique of photometric analysis and has studied the operating instructions for the spectrophotometer or photometer.

7. MEASUREMENT CONDITIONS

When performing measurements in the laboratory, the following conditions must be met:

· ambient temperature (22 ± 6) °C;

· atmospheric pressure (84 - 106) kPa;

· relative humidity no more than 80% at a temperature of 25 ° C;

· AC frequency (50 ± 1) Hz;

· mains voltage (220 ± 22) V.

8. SAMPLE COLLECTION AND STORAGE

8.1. Sampling is carried out in accordance with the requirements of GOST R 51592-2000 “Water. General requirements for sampling."

8.2. Dishes intended for collecting and storing samples are washed with a saturated solution of soda ash (sodium carbonate) and then with distilled water. When washing heavily soiled dishes, it is recommended to use a chrome mixture, then rinse thoroughly (at least 10 times) with tap water and rinse with distilled water.

8.3. Water samples are taken in glass bottles with tightly screwed caps with liners that ensure tightness, with a capacity of 0.5 dm 3.

The volume of the sample taken must be at least 0.5 dm.

8.4. Samples are analyzed no later than 6 hours after sampling when stored at a temperature above 10 ° C without a preservative, or within 10 days when preserved with sulfuric acid at the rate of 5 cm 3 of acid solution (1: 1) per 1 dm 3 of water.

8.5. When taking samples, an accompanying document is drawn up in the approved form, which indicates:

Purpose of analysis, suspected pollutants,

Place, time of selection,

Sample number,

Position, surname of the sample taker, date.

9. PREPARATION FOR MEASUREMENTS

9.1. Preparation of solutions and reagents

9.1.1. Distilled water purified from formaldehyde.

Distilled water is boiled for 30 minutes and cooled to room temperature. Use on the day of preparation.

9.1.2. Sulfuric acid solution, 1:1.

To 100 cm 3 of distilled water placed in a heat-resistant beaker, with continuous stirring, add 100 cm 3 of concentrated sulfuric acid and cool. The solution is stable when stored in a tightly closed bottle for 1 year.

9.1.3. Hydrochloric acid solution, 2:1.

340 cm 3 of concentrated hydrochloric acid is added to 170 cm 3 of distilled water and stirred. The solution is stable when stored in a tightly sealed container for 6 months.

9.1.4. Potassium or sodium hydroxide solution, 2 mol/dm3.

56 g of KOH or 40 g of NaOH are dissolved in 500 cm 3 of distilled water. The solution is stable when stored in tightly closed polyethylene containers for 3 months.

9.1.5. Starch solution, 0.5%.

Shake 0.5 g of starch with 15 - 20 cm 3 of distilled water. The suspension is gradually poured into 80 - 85 cm 3 of boiling distilled water and boiled for another 2 - 3 minutes. After cooling, preserve by adding 2 - 3 drops of chloroform. Store for no more than 1 month.

9.1.6. Standard solution of potassium dichromate with a concentration of 0 .0200 mol/dm 3 equivalents.

When using a standard titer, the latter is dissolved in distilled water in a volumetric flask with a capacity of 500 cm 3, then 50 cm 3 of the resulting solution is taken, transferred to a volumetric flask with a capacity of 500 cm 3 and the volume is adjusted to the mark with distilled water.

To prepare a standard solution from a sample of 0.4904 g of K 2 Cr 2 O 7, pre-dried in an oven at 105 ° C for 1 - 2 hours, transfer quantitatively into a volumetric flask with a capacity of 500 cm 3, dissolve in distilled water and bring the volume of the solution to the mark on the flask. Store in a bottle with a well-ground stopper in a dark place for no more than 6 months.

9.1.7. Standard sodium thiosulfate solution with a concentration of 0.02 0 mol/dm 3 equivalents.

When using a standard titer, the latter is dissolved in distilled water, previously boiled for 1.5 hours and cooled to room temperature, in a volumetric flask with a capacity of 500 cm 3, then 50 cm 3 of the resulting solution is taken, transferred to a volumetric flask with a capacity of 500 cm 3 and bring the volume to the mark with boiled distilled water.

To prepare a standard solution from a sample of 5 g of Na 2 S 2 O 3? 5H 2 O, dissolve in 1 dm 3 of distilled water, previously boiled for 1.5 hours and cooled, and bring the volume of the solution to the mark on the flask. As a preservative, 2 cm 3 of chloroform is added to the resulting solution.

Before determining the exact concentration, the solution is kept for at least 5 days. Store in a dark glass bottle for no more than 4 months.

The exact concentration of the standard sodium thiosulfate solution is determined as described in Appendix A at least once a month.

9.1.8. Iodine solution, 0.02 mol/dm 3 equivalents.

When using a standard titer, the latter is dissolved in distilled water in a volumetric flask with a capacity of 500 cm 3.

When preparing a solution from a sample, 4 - 5 g of KI is dissolved in a small amount (20 - 25 cm 3) of distilled water, 1.3 g of crystalline iodine is added; after dissolving it, add another 480 cm 3 of distilled water and mix.

The solution is stored in a dark glass bottle.

The exact concentration of the iodine solution is determined at least once a month, as described in Appendix A.

9.1.9. Acetic acid solution, 1:4.

Mix 1 volume of acetic acid with 4 volumes of distilled water that does not contain formaldehyde. The solution is stable when stored in a tightly sealed container for 3 months.

9.1.10. Acetyl acetone solution, 5%.

Add 2 cm 3 of acetylacetone to 38 cm 3 of distilled water and stir until completely dissolved. Store in the refrigerator in a bottle with a ground stopper for no more than 10 days.

9.1.11. Ammonium acetate buffer solution.

To 80 cm 3 of glacial acetic acid add 90 cm 3 of concentrated ammonia solution and mix. The pH value of the resulting buffer solution should be 5.9 - 6.5. Store in a tightly closed bottle for no more than 3 months.

9.2. Preparation of calibration solutions

Calibration solutions certified according to the preparation procedure are prepared from a standard sample (SS) or a 40% formaldehyde solution (formalin).

When using CO, dilute the original solution in accordance with the instructions for its use.

The preparation of a calibration solution from formalin is carried out in accordance with paragraphs 9.2.1 - 9.2.3.

9.2.1. Formaldehyde solution (A).

In a volumetric flask with a capacity of 100 cm 3, 2.5 cm 3 of a solution of potassium or sodium hydroxide, 2.5 cm 3 of distilled water and 1 cm 3 of a 40% formaldehyde solution are sequentially pipetted. The volume of the solution is adjusted to the mark with distilled water and mixed. To determine the exact concentration of formaldehyde, 1 cm 3 of the resulting solution is taken into a conical flask with a ground stopper with a capacity of 250 cm 3, 20 cm 3 of iodine solution and 10 cm 3 of potassium or sodium hydroxide solution are added with a pipette. The flask is capped and left to stand for 15 minutes in a dark place. Then add 5 cm 3 of hydrochloric acid solution, mix and leave for another 10 minutes in a dark place.

The released excess iodine is titrated with a solution of sodium thiosulfate to a pale yellow color, 1 cm 3 of starch solution is added and titration is continued until the solution becomes discolored.

The determination is repeated 1 - 2 more times and if there is no discrepancy in the volumes of sodium thiosulfate solution by more than 0.05 cm 3, the average value is taken as the result.

The mass concentration of formaldehyde in the main solution (A) is calculated using the formula:

where C f is the mass concentration of formaldehyde solution, mg/dm 3 ;

C and - concentration of iodine solution, mol/dm 3 equivalents;

V and - volume of added iodine solution, cm 3;

C t - concentration of sodium thiosulfate solution, mol/dm 3 equivalents;

Vt is the volume of sodium thiosulfate solution consumed for titrating the excess iodine solution, cm 3;

V f - volume of formaldehyde solution taken for titration, cm 3.

The main solution of formaldehyde is stored in the refrigerator for no more than 1 month. Its exact concentration is established before use for preparing intermediate and working solutions.

9.2.2. A solution with a mass concentration of formaldehyde of 0.100 mg/cm 3 (B).

The volume of solution A that must be taken to obtain 100 cm 3 of solution B with a concentration of 0.100 mg/dm 3 is calculated using the formula:

where Vf is the volume of solution A, cm 3;

C f is the mass concentration of formaldehyde in solution A, mg/cm 3 .

Using a graduated pipette, the calculated volume of solution A is placed into a 100 cm 3 volumetric flask, adjusted to the mark with distilled water and mixed. The solution is stored for no more than a day.

9.2.3. A solution with a mass concentration of formaldehyde 5 μg /cm 3 (V).

5.0 cm 3 of formaldehyde solution B is transferred to a volumetric flask with a capacity of 100 cm 3, adjusted to the mark with distilled water (section 9.1.1) and mixed. The solution is used on the day of preparation.

9.3. Construction of a calibration graph

To construct a calibration curve, it is necessary to prepare samples for calibration containing 0 - 0.10 μg of formaldehyde in 25 cm 3 of solution.

The conditions for conducting the analysis must comply with clause 7.

The composition and number of samples for constructing the calibration graph are given in Table 2.

For all calibration solutions, errors due to the preparation procedure do not exceed 3% relative to the assigned value of the mass concentration of formaldehyde.

When constructing a calibration graph, 20 cm 3 of distilled water is added to volumetric flasks with a capacity of 25 cm 3 (clause 9.1.1), and aliquots of formaldehyde B solution are added using graduated pipettes with a capacity of 1 or 2 cm 3 in accordance with Table. 2, bring the volumes of solutions in the flasks to the mark, mix and transfer to conical flasks with a capacity of 100 cm 3.

table 2

Composition and number of samples for calibration when determining formaldehyde

The analysis of samples for calibration is carried out in increasing order of their concentration according to paragraph 10, excluding the distillation stage.

The optical density of samples with formaldehyde additives and a blank (not containing additive) sample is measured at? = 412 nm, photometering 3 times in order to exclude random results and averaging the data. The average optical density of a blank sample is subtracted from the average optical density of samples with formaldehyde additives.

The calibration graph is plotted in coordinates: formaldehyde content in the calibration sample, μg - optical density.

9.4. Monitoring the stability of the calibration characteristic

The stability of the calibration characteristic is monitored at least once a month or when changing the main reagents (acetylacetone, ammonium acetate, buffer solution). The means of control are newly prepared samples for calibration (at least 3 samples from those given in Table 2).

The calibration characteristic is considered stable when the following condition is met for each calibration sample:

|X- C| ? 1,96?RL,

Where X- the result of a control measurement of the mass concentration of formaldehyde in the calibration sample;

WITH- certified value of the mass concentration of formaldehyde in the sample for calibration;

?RL- standard deviation of intra-laboratory precision, established when implementing the technique in the laboratory.

Note . It is permissible to establish the standard deviation of intra-laboratory precision when implementing a technique in a laboratory based on the expression: ? RL = 0,84?R, with subsequent clarification as information accumulates in the process of monitoring the stability of the analysis results.

Meanings? R are given in table 1.

If the stability condition of the calibration characteristic is not met for only one calibration sample, it is necessary to re-measure this sample in order to eliminate the result containing a gross error.

If the calibration characteristic is unstable, find out the reasons for its instability and repeat the stability control using other calibration samples provided for in the methodology. If instability of the calibration characteristic is detected again, a new calibration graph is built.

10. TAKE MEASUREMENTS

A water sample with a volume of 200 cm 3 is placed in a distillation flask (if preservation was carried out, the sample is first neutralized with a solution of KOH or NaOH to pH 7 - 8 on universal indicator paper), 25 g of sodium sulfate are added, the parts of the formaldehyde distillation unit are connected and distilled into a graduated cylinder 100 cm 3 distillates.

The distillate is thoroughly mixed with a glass rod, pipetted 25 cm 3, placed in a conical flask with a capacity of 100 cm 3, add 2 cm 3 of ammonium acetate buffer solution (or 2.0 g of ammonium acetate and 0.5 cm 3 of acetic acid solution 1:4 ) and 1.0 cm 3 acetylacetone solution. The mixture is stirred until the reagents are completely dissolved and kept in a water bath for 30 minutes at (40 ± 3) °C. Simultaneously with the sample, a blank determination is performed using 25 cm 3 of distilled water that does not contain formaldehyde.

The optical density of solutions relative to distilled water is measured at 412 nm in cuvettes with an absorbing layer thickness of 5 cm. The optical density of the blank experiment is subtracted from the optical density of the sample.

If the measured optical density of the sample exceeds the optical density corresponding to the last point of the calibration curve, repeat the determination with a smaller aliquot of the distillate, diluted to a volume of 25 cm 3 with distilled water that does not contain formaldehyde (clause 9.1.1).

11. PROCESSING OF MEASUREMENT RESULTS

Mass concentration of formaldehyde in the analyzed water X, mg/dm 3, calculated by the formula:

100 - volume of distillation, cm 3;

1.2 - coefficient taking into account the degree of formaldehyde distillation from the water sample;

V d - volume of distillation aliquot, cm 3;

V in - volume of water sample taken for distillation, cm 3.

The discrepancy between the analytical results obtained in two laboratories should not exceed the reproducibility limit. If this condition is met, both analysis results are acceptable, and their arithmetic mean can be used as the final value.

The value of the reproducibility limit R at P = 0.95 for the entire regulated range of measurements of the mass concentration of formaldehyde is 22%.

If the reproducibility limit is exceeded, methods for checking the acceptability of analysis results can be used in accordance with section 5 of GOST R ISO 5725-6.

12. REGISTRATION OF ANALYSIS RESULTS

Analysis result X in documents providing for its use, it can be presented in the form:

X ±?, mg/dm3, P = 0.95,

Where? - indicator of the accuracy of the technique.

Meaning? calculated by the formula:

0.01? d? X.

The d value is given in Table 1.

It is acceptable to present the result of the analysis in documents issued by the laboratory in the form:

X ± ? l, mg/dm 3 , P = 0.95,

given that? l < ?,

Where X- the result of the analysis obtained in accordance with the instructions in the methodology;

±? l- the value of the error characteristic of the analysis results, established during the implementation of the technique in the laboratory, and ensured by monitoring the stability of the analysis results.

The numerical values ​​of the measurement result must end with a digit of the same digit as the values ​​of the error characteristic.

13. QUALITY CONTROL OF ANALYSIS RESULTS WHEN IMPLEMENTING THE METHOD IN THE LABORATORY

Quality control of analysis results when implementing the technique in the laboratory includes:

Operational control of the analysis procedure (based on the assessment of the error in the implementation of a separate control procedure);

Monitoring the stability of analysis results (based on monitoring the stability of standard deviation of repeatability, standard deviation of intra-laboratory precision, error).

13.1. Algorithm for operational control of the analysis procedure using the additive method

K k with control standard TO.

TOTo calculated by the formula:

K k = |X" - X - C d |,

Where X" - the result of analyzing the mass concentration of formaldehyde in a sample with a known additive;

X- the result of the analysis of the mass concentration of formaldehyde in the original sample;

S d- amount of additive.

Control standard TO calculated by the formula:

Where? l,X", ?l,x- values ​​of the error characteristic of the analysis results, established in the laboratory when implementing the method, corresponding to the mass concentration of formaldehyde in the sample with a known additive and in the original sample, respectively.

Note . l= 0.84? ?, with subsequent clarification as information accumulates in the process of monitoring the stability of the analysis results.

K k ? TO. (1)

If condition (1) is not met, the control procedure is repeated. If condition (1) is not met again, the reasons leading to unsatisfactory results are clarified and measures are taken to eliminate them.

13.2. Algorithm for operational control of the analysis procedure using samples for control

Operational control of the analysis procedure is carried out by comparing the result of a separate control procedure K k with control standard TO.

Result of the control procedure TOTo calculated by the formula:

K k = |X k - WITH|,

Where X k- the result of the analysis of the mass concentration of formaldehyde in the control sample;

WITH- certified value of the control sample.

Control standard TO calculated by the formula

K = ?l,

where ±? l- characteristic of the error of the analysis results corresponding to the certified value of the control sample.

Note . It is permissible to characterize the error of analysis results when introducing a technique in a laboratory based on the expression: ? l= 0.84? ? with subsequent clarification as information accumulates in the process of monitoring the stability of the analysis results.

The analysis procedure is considered satisfactory if the following conditions are met:

K k ? TO. (2)

If condition (2) is not met, the control procedure is repeated. If condition (2) is not met again, the reasons leading to unsatisfactory results are determined and measures are taken to eliminate them.

The frequency of operational control of the analysis procedure, as well as the implemented procedures for monitoring the stability of analysis results, are regulated in the Laboratory Quality Manual.

Appendix A
(required)

Establishing the exact concentration of standard solutions of sodium thiosulfate and iodine

A.1. Sodium thiosulfate solution

Add 80 - 90 cm 3 of distilled water, 10.0 cm 3 of a standard solution of potassium dichromate to the titration flask, add 1 g of dry KI and 10 cm 3 of hydrochloric acid solution. The solution is stirred, kept in a dark place for 5 minutes, and the sample is titrated with sodium thiosulfate solution until a faint yellow color appears. Then add 1 cm 3 of starch solution and continue titration drop by drop until the blue color disappears. The titration is repeated and, if the discrepancy between the titrant volumes does not exceed 0.05 cm 3, their average value is taken as the result. Otherwise, repeat the titration until results are obtained that differ by no more than 0.05 cm 3 .

The exact concentration of sodium thiosulfate solution is found using the formula:

where C t is the concentration of sodium thiosulfate solution, mol/dm 3 equivalent;

C d - concentration of potassium bichromate solution, mol/dm equivalent;

V t is the volume of sodium thiosulfate solution used for titration, cm 3 ;

V d - volume of potassium dichromate solution taken for titration, cm 3.

A.2. Iodine solution

60 - 70 cm 3 of distilled water are added to the titration flask, 20 cm 3 of iodine solution and 10 cm 3 of hydrochloric acid solution are added with a pipette and titrated with sodium thiosulfate to a pale yellow color. Then add 1 cm 3 of starch solution and titrate drop by drop until the solution becomes discolored. Titration is repeated 1 - 2 more times and if there is no discrepancy in the volumes of sodium thiosulfate solution by more than 0.05 cm 3, the average value is taken as the result.

Group K29

INTERSTATE STANDARD

FURNITURE, WOOD AND POLYMER MATERIALS

Method for determining the release of formaldehyde and other harmful volatiles

chemicals in climate chambers

Furniture, timber and polymers.

Method for determination of formaldehyde and other volatile chemicals in

the air of climatic chambers

OKS 79.97.140

Date of introduction

Preface

1 DEVELOPED by the All-Russian Design and Engineering Technological Institute of Furniture (VPKTIM), All-Russian Research Institute woodworking industry (VNIIDrev) and the Scientific and Practical Center for Hygienic Expertise of the State Committee for Sanitary and Epidemiological Supervision of Russia

INTRODUCED by the Technical Secretariat of the Interstate Council for standardization , metrology and certification

2 ADOPTED by the Interstate Council for Standardization, Metrology and Certification

State name	Name of the national standardization body
Republic of Belarus	Belstandart
The Republic of Moldova	Moldovastandard
The Republic of Kazakhstan	Gosstandart of the Republic of Kazakhstan
	State Standard of Ukraine
Russian Federation	Gosstandart of Russia

3 By Decree of the Committee of the Russian Federation on Standardization, Metrology and Certification dated August 23, 1995 N 448, interstate standard GOST put into effect directly as state standard Russian Federation with July 1 1996

4 INTRODUCED FOR THE FIRST TIME

1 AREA OF USE

This standard establishes a method for determining in climatic chambers the release of formaldehyde and other harmful volatile substances into the air from furniture products, particle boards and fibreboards, plywood, parts and blanks made from them, parquet products, as well as polymer and structural materials used in their manufacture. , facing, finishing and adhesive materials.

GOST 8.207-76 GSI. Direct measurements with multiple observations. Methods for processing observation results. Basic provisions

GOST 1770-74 Laboratory glassware. Cylinders, beakers, flasks, test tubes. Specifications

GOST 3117-78 Ammonium acetate. Specifications

GOST 3118-77 Hydrochloric acid. Specifications

GOST Soluble starch. Specifications

GOST Acetyl acetone. Specifications

GOST Furniture. General technical conditions

GOST Chairs for auditoriums. General technical conditions

GOST Furniture for sitting and lying. General technical conditions

GOST Furniture for educational institutions. Specifications

3 TESTING EQUIPMENT AND AUXILIARY DEVICES

3.1 Climate chambers with a working space volume from 0.12 to 50 m

3.1.1 The design of the chamber must ensure tightness, automatic temperature control, humidity. To line the internal surfaces of the chamber, materials with low sorption capacity (stainless metal, glass) should be used.

3.1.2 The ventilation system must ensure uniform air circulation throughout the entire working volume of the chamber with installed samples.

3.1.3 The following parameters must be maintained in the working volume of the chamber during testing:

air temperature - (23±2) °C;

relative air humidity - (45±5)%;

air exchange per hour - 1±0.1.

Testing of parquet products is carried out at air exchange (0.5±0.05) per hour.

3.2 Aspiration device with a flow meter to determine the speed or volume of air.

3.3 Absorption devices of the Polezhaev, Richter type, with porous plates.

3.4 Chromatographs, spectrophotometers, electrophotocolorimeters, providing determination of the content of a volatile chemical substance in the sampled air (selected depending on the type of substance being determined).

3.5 Laboratory scales with the largest weighing limit of 500 g with a weighing error of ±0.02 g.

3.6 Analytical balances with the largest weighing limit of 200 g with a weighing error of ±0.0005 g.

3.7 Aneroid barometer.

3.8 Stopwatch with a second division value of 0.2 s.

3.9 Psychrometer or other device for monitoring air temperature and humidity.

3.10 Universal measuring instruments for measuring sample dimensions with an error of ±1 mm.

3.11 Measuring instruments, auxiliaries, materials, chemical reagents, laboratory glassware - in accordance with methods for determining harmful volatile chemicals approved by authorities sanitary and epidemiological surveillance.

4 SAMPLE SELECTION AND PREPARATION

4.1 To test furniture products, samples are taken in quantities that create a given saturation of the chamber volume:

For cabinet furniture, tables, beds - 1 m of sample surface area per 1 m of climate chamber volume;

For furniture products for sitting and lying - 0.3 m of sample surface area per 1 m of climate chamber volume.

The surface area of ​​the samples is calculated with an error of ±3%. It includes the total area on both sides of all furniture parts (surfaces of back walls, bottoms of drawers, shelves, surfaces behind mirrors, plugs in furniture for sitting and lying, etc.).

As a rule, furniture products selected for physical and mechanical tests are subjected to tests in a climate chamber in accordance with the requirements of GOST 16371, GOST 19917, GOST 22046, GOST 16854.

4.2 To test parts and blanks, parquet products, as well as structural, facing, finishing and adhesive materials, take at least 3 samples made in accordance with the technical documentation.

4.2.1 Paints and varnishes are applied to the surface of glass, tin or wood according to the consumption rates used in the production of materials, parts and products.

4.2.2. Adhesive materials are applied to the surface of glass, tin or wood according to the consumption rates used in production, and a sample of the material for which the adhesive is intended is glued.

4.2.3 Samples of wood boards and plywood are taken from the area of ​​the board located at a distance of at least 300 mm from its edges.

4.2.4 Samples of polymer and facing materials are presented with dimensions that create the specified saturation.

4.2.5 The area of ​​the sample (according to the layers on both sides), intended for testing in chambers with a volume of 0.12 to 1 m inclusive, is calculated with an error of ±3%, based on the saturation of 1 m of the sample surface area per 1 m of chamber volume.

The area of ​​parquet product samples is determined only from the front side. Saturation for parquet products is taken equal to 0.4 m of sample surface area per 1 m of chamber volume. The dimensions of the samples in length and width are determined based on the internal dimensions of the climatic chambers.

4.2.6 If the release of harmful volatile chemicals through sheets is being assessed, the edges of the samples should have a sealed protective coating (edge ​​plastic, aluminum foil glued with silicate glue, etc.).

The edges of parquet product samples are not protected.

4.2.7 Transportation and storage of samples - in accordance with regulatory documents for tested products and materials.

4.3 Testing of samples made using adhesives or adhesive joints is carried out no earlier than 7 days after their manufacture, unless otherwise specified in regulatory documents.

Before testing, furniture products made of wood and wood materials are kept for at least 3 days in a room with a relative air humidity of 45 to 70% and a temperature of 15 to 30 °C.

4.4 Samples submitted for testing must be accompanied by a passport containing their characteristics (Appendix A).

5 TESTING

5.1 Preparation for the test

5.1.1 Testing of particle boards, wood-fiber boards, plywood, parts and blanks made from them, parts of parquet products, structural, facing, finishing, polymer and adhesive materials is carried out in climatic chambers with a volume of 0.12 to 1 m inclusive.

Testing of furniture products is carried out in chambers with a volume of more than 1 m , allowing these products to be placed in accordance with specified conditions.

5.1.2 Samples are placed in the chamber on a stand or in another way that ensures free air circulation, and the contact area should not exceed 0.5% of the surface area of ​​the sample.

5.1.3 Samples of parquet products are placed on the floor of the chamber, the front surface of the samples should be turned upward. Another method of installing samples is allowed, but their non-working surface must be protected with a gas-tight material (foil, etc.).

5.1.4 Furniture items are placed in the chamber, evenly distributing them over the floor area. Products must be located at a distance of at least 0.1 m from each other and from the walls of the chamber. Product doors must be open to an angle of at least 30°, drawers must be extended at least a third of their length.

5.1.5 In chambers with a volume of more than 1 m (Figure 1), tubes for air sampling are fixed and connected to the corresponding outlets of the chamber.

In chambers with a volume of up to 1 m inclusive, air sampling can be carried out through one outlet.

5.1.6 After placing the samples, close the chamber doors hermetically. Includes air conditioning and ventilation air and, after reaching the specified parameters, set the automatic operating mode of the chamber.

The operating parameters of the air are monitored by instruments included in the chamber design and by a control device that operates autonomously.

5.2 Carrying out tests in chambers with a volume of up to 1 m inclusive

5.2.1 Throughout the test, air samples are taken from the working volume of the chamber at specified intervals.

The first air sampling is carried out 24 hours after stabilization of the air parameters in the chamber in accordance with the requirements of 3.1.3. The second, third and subsequent selections are carried out every 24 hours for 5 days from the start of the test.

5.2.2 In this case, when, based on the results of three consecutive samplings, it is established that the concentration of volatile substances in the chamber is constant (i.e., the standard deviation of the measurement results is no more than 15%), the test is stopped before the expiration of 5 days.

5.2.3 Simultaneously with sampling from the climate chamber, air supplied to the chamber is sampled.

5.2.4 Air sampling is carried out using an aspiration device (3.2) and absorption devices (3.3), selected depending on the type of controlled substances and the method for determining their concentration.

5.2.5 Air samples are analyzed on the day of collection in accordance with methods for measuring the concentration of harmful volatile chemicals approved by sanitary and epidemiological supervision authorities. To determine the concentration of harmful volatile chemicals, photoelectrocolorimeters, spectrophotometers or chromatographs of any type are used that provide the necessary resolution and measurement error (3.4 and 3.5).

5.2.6 The procedure for determining formaldehyde with an acetylacetone reagent (colorimetric method) is given in Appendix B. To determine the concentration of formaldehyde, use a spectrophotometer or photoelectrocolorimeter.

5.2.7 The measurement results are recorded in the work log.

5.3 Testing furniture products in chambers with a volume of more than 1 m

5.3.1 The first sampling of air from the chamber and control sampling of air at the entrance to the chamber are carried out 72 hours after the operating mode of the air in the chamber has been established.

5.3.2 Subsequent air sampling is carried out every 24 hours.

5.3.3 In the case when, based on the results of three consecutive samplings, it is established that the concentration of the controlled volatile substances is constant (the standard deviation of the measurement results does not exceed 15%), the test is stopped.

After 21 days, the test is stopped regardless of the concentration of the controlled volatile substances.

5.3.4 Air sampling is carried out at six points shown in Figure 1, located at two levels of chamber height.

I - air sampling levels (750; 1500 mm); // - sampling tubes

air from the chamber; 1 ; 2; 3; 4; 5; 6 - air sampling points

Picture 1

At each level, three points are determined, evenly distributed along the length and width of the chamber.

It is allowed to take air samples from a smaller number of points, but not less than two, located at different altitude levels.

5.3.5 Air sampling and analysis are carried out in accordance with 5.2.3-5.2.7.

6 PROCESSING OF TEST RESULTS

6.1 The concentration of volatile chemicals in the air of the climate chamber in milligrams per cubic meter is calculated in accordance with the methods for measuring controlled substances (5.2.5).

6.2 The absolute value of the concentration of a volatile chemical substance emitted by the test sample into the air of the climatic chamber is calculated using the formula

where is the concentration of the volatile substance in the air of the climatic chamber, mg/m;

Concentration of volatile substance in the air entering the chamber, mg/m.

6.3 The concentration value of a volatile chemical substance released into the air of a climatic chamber with a volume of up to 1 m inclusive is found as the arithmetic mean value of the test results of at least three samples according to the formula

where is the number of observation repetitions.

6.4 Standard deviation of measurement results, %, is determined by the formula

. (3)

6.5 Concentration of the volatile chemical for each measurement made in accordance with 5.3.1, 5.3.2 and 5.3.4 in chambers larger than 1 m , determined as the arithmetic mean of the measurement results at various points in the chamber according to formula (2).

6.6 The final value of the concentration of a harmful volatile chemical in climatic chambers with a volume of more than 1 m when testing furniture products is calculated as the arithmetic mean value () measurement results for the last three air samples, calculated using formulas (1) and (2). The standard deviation is determined by formula (3).

In the case when the concentration of a substance is constant (5.3.3) in three consecutive measurements, the arithmetic mean value is taken as a characteristic of the controlled parameter.

In the case when the concentration of a substance is not constant (decreases or increases), the concentration value obtained during the last selection and calculated according to formula (1) is taken as a characteristic.

6.7 The test results are assessed by comparing them with the maximum permissible concentrations of harmful substances in the atmospheric air, approved in the prescribed manner by the State Sanitary and Epidemiological Supervision authorities.

6.8 Samples are considered to have passed the test if the results obtained are less than or equal to the standards established in the regulatory documents for the products.

6.9 Test results are documented in a protocol (Appendix B).

Form of passport of the sample submitted for testing

PASSPORT

name of the sample, product, set of furniture, project, designation,
index (if available)
Name of manufacturer (customer)
Sample production date
Name of regulatory documentation for products
for products and materials

Characteristics of samples:

The sample was made using the following materials:

1 Slab

Name of material

Designation (brand) according to ND

formaldehyde emissions using a hammer drill

Sample size

Note*

Wood-chip

Fiberboard

* If necessary, indicate the type of binder and other characteristic features of the sample.

2 Facing materials, flooring and other polymer materials

Name of material

Designation of regulatory documentation

Basic chemical composition (if necessary)

Sample size

Intelligence about permission for use

Name of material

Designation of regulatory documentation

Sample size

Intelligence about permission material for use

Note - Depending on the type and purpose of the test, other information is provided in agreement with the testing laboratory.

	Signatures of the customer’s manager and the person responsible for communication with the testing laboratory (center), transcript of signatures, date

APPENDIX B

(required)

METHOD FOR DETERMINING FORMALDEHYDE

WITH ACETYLACETONE REAGENT

B.1 SCOPE OF APPLICATION

This method is intended to determine the concentration of formaldehyde in the air of residential premises and climatic chambers.

B.2 ESSENCE AND CHARACTERISTICS OF THE METHOD

The method is based on the reaction between formaldehyde and acetylacetone reagent in acetic acid. ammonium with the formation of a yellow-colored product.

The lower detection limit of formaldehyde is 0.001 mg in 10 cm of the analyzed solution.

Determination error ±10%.

The range of measured concentrations of formaldehyde in atmospheric air, indoor air and climatic chambers is from 0.008 to 1.3 mg/m with an air sample of at least 120 dm.

The determination of formaldehyde does not interfere with methyl and ethyl alcohols, ethylene glycol, hydrogen sulfide, ammonia.

B.3 MEASURING INSTRUMENTS AND AUXILIARY DEVICES

B.3.1 Aspiration device providing an air flow rate of 2 dm/min.

B.3.2 Spectrophotometer or photoelectrocolorimeter with a light filter with maximum light absorption at a wavelength of 412 nm and a cuvette with a working layer width of 10 mm.

B.3.3 Volumetric flasks 50, 250 and 1000 cm according to GOST 1770.

B.3.4 Conical flasks 100 cm according to GOST 1770.

B.3.5 Absorption devices of the Polezhaev, Richter type.

B.4 REAGENTS AND SOLUTIONS

B.4.1 Acetyl acetone, analytical grade. according to GOST 10259.

B.4.2 Acetic acid, glacial x. h.

B.4.3 Ammonium acetate, analytical grade. according to GOST 3117.

B.4.4 Formalin, 40% formaldehyde solution.

B.4.5 Caustic soda, analytical grade. 30% solution.

B.4.6 Hydrochloric acid, conc. analytical grade according to GOST 3118, diluted 1:5.

B.4.7 Sodium sulfate NSO·fixanal, 0.1N solution.

B.4.8 Iodine, fixanal 0.1 N solution.

B. 4.9 Soluble starch according to GOST 10163, 1% solution.

B.4.10 Acetyl acetone reagent: 200 g of ammonium acetate is dissolved in 800 cm of water in a 1 dm volumetric flask. 3 cm of acetylacetone and 5 cm of acetic acid are added to the solution and the solution in the flask is brought to the mark with water (absorption solution).

B.4.11 Initial solution for calibration: 5 cm of formalin is added to a 250 cm volumetric flask and diluted with water to the mark. Then the formaldehyde content in this solution is determined. To do this, 5 cm of solution is placed in a 250 cm conical flask with a ground-in stopper, 20 cm of 0.1 N iodine solution is added and a 30% sodium hydroxide solution is added drop by drop until a stable pale yellow color appears. The flask is left for 10 minutes, then a solution of 2.5 cm of hydrochloric acid (diluted 1:5) is carefully acidified, left for 10 minutes in the dark, and the excess iodine is titrated with a 0.1 N solution of sodium thiosulfate. When the solution turns light yellow, add a few drops of starch. The amount of thiosulfate consumed for titration of 20 cm of 0.1 N iodine solution is preliminarily established. Based on the difference between the amount spent on the control titration and the excess iodine that did not react with formaldehyde, the amount of iodine that was used for the oxidation of formaldehyde is determined. 1 cm of 0.1 N iodine solution corresponds to 1.5 mg of formaldehyde. Having established the formaldehyde content in 1 cm of solution, initial and working solutions of formaldehyde containing 0.1 mg/cm and 0.01 mg/cm, respectively, are prepared by appropriate dilution with water. The formaldehyde content in solutions is determined titrimetrically.

B.5 SAMPLING

B.5.1 When testing polymer materials and products in climatic chambers, sample preparation and sampling procedures are carried out in accordance with sections 4 and 5 of this standard.

B.5.2 To determine the maximum single concentration of formaldehyde in the air of a climatic chamber or enclosed space, air is aspirated at a speed of 2 dm/min in a volume of 60-120 dm through two series-connected absorption devices of the Polezhaev, Richter type, filled with 7 cm of absorption solution and 3 cm distilled water. During the sampling process, a non-volatile derivative of formaldehyde is formed.

B.5.3 At the same time, a control sample of the air supplied to the climate chamber is taken.

Sampling is carried out in accordance with 5.2.

B.6 PROGRESS OF ANALYSIS

B.6.1 The selected samples are placed in a water bath heated to 40 °C and kept for 30 minutes.

B.6.2 After cooling the samples, measure the optical density of colored solutions using a spectrophotometer or photoelectrocolorimeter at a wavelength of 412 nm in cuvettes with a working layer width of 10 mm. The quantitative content of formaldehyde in the sample is assessed using the calibration characteristic.

B.7 ESTABLISHING CALIBRATION CHARACTERISTICS

B.7.1 Pipette the working solution of formaldehyde (B.4.11) into a 10 cm measuring tube (B.4.11), water with a 5 cm pipette, bring the absorption solution to the mark and prepare solutions for calibration in accordance with Table B.1 (when determining low concentrations of formaldehyde) and table B.2 (when determining high concentrations of formaldehyde).

Solutions, cm
Working solution of formaldehyde containing 0.01 mg/cm
Acetyl acetone reagent	7 cm in each tube

Note - When preparing solutions 1 and 2, use a capillary pipette or an automatic microdispenser.

Solutions, cm	Numbers of solutions for calibration
Initial solution of formaldehyde containing 0.1 mg/cm
Acetyl acetone reagent	7 cm in each tube

B.7.2 Calibration solutions are heated in a water bath for 30 minutes at T - 40 °C, cooled and their optical density is measured (wavelength is 412 nm, the width of the working layer of the cuvette is 10 mm). - atmospheric pressure, mbar;

- air sample volume, m;

Optical density of the analyzed sample, calculated as the difference between the sum of the optical densities of the analyzed solutions in 2 absorbers and a zero (blank) solution;

0.00371 - coefficient of reduction to normal conditions.

Test report form

name of the accredited testing laboratory (center)

number and date of the accreditation certificate in the GOST R certification system

postal address and telephone number of the testing laboratory (center)

I APPROVED Head of testing laboratory (center)

full name

PROTOCOL N

type of test

name and designation of tested samples

1 Manufacturer

name and address

2 Date of manufacture and sampling

3 Basis for testing

letter number and date

(agreement) of the customer

4 Designation of regulatory documentation for products

5 Determined indicators

list of defined

controlled indicators

6 List (designation) of regulatory documents

on test methods

7 List of certified testing equipment

designation, number and date of the certificate (certificate, hallmarks)

8 Sample characteristics

9 Test conditions

temperature and relative

air humidity in the chamber, saturation, air exchange

10 Test results

text or tables

indicating standard values

11 Conclusion

Artist signatures

job title

full name

The text of the document is verified according to:

official publication

M.: IPK Standards Publishing House, 1995