GB/T 18204.2-2025 Examination methods for public places - Part 2: Chemical indicators
1 Scope
This document describes the methods for determining chemical indicators in indoor air of public places, urea and oxidation-reduction potential of swimming pool water.
This document is applicable to the determination of chemical indicators in indoor air of public places, urea and oxidation-reduction potential of swimming pool water. Other places, rooms and other indoor environments shall be implemented with reference.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies..
GB/T 11742 Standard method for hygienic examination of hydrogen sulfide in air of residential areas - Methylene blue spectrophotometric method
GB/T 14669 Air quality - Determination of ammonia - Ion selective electrode method
GB/T 16129 Standard method for hygienic examination of formaldehyde in air of residential areas - Spectrophotometric method
GB/T 18883 Indoor air quality standard
HJ 590-2010 Ambient air - Determination of ozone - Ultraviolet photometric method
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
standard state
air state at a temperature of 0°C (or absolute temperature of 273.15 K) and an atmospheric pressure of 101.325 kPa
4 Carbon monoxide
4.1 Non-dispersive infrared analysis method
4.1.1 Principle
Carbon monoxide (CO) selectively absorbs infrared rays. Within a certain range, the absorption value is linearly related to the concentration of carbon monoxide, and the concentration of carbon monoxide in the sample may be determined based on the absorption value.
4.1.2 Apparatus
The indicators of the non-dispersive infrared carbon monoxide gas analyzer used for measurement are as follows:
——Measuring range: 0.125 mg/m3 ~ 62.5 mg/m3;
——Reproducibility: within ±1% full scale;
——Zero drift: within ±2% full scale/h;
——Range drift: within ±2% full scale/3h;
——Linear deviation: within ±2% full scale;
——Response time: t90%<45 s.
4.1.3 Reagents and materials
The reagents and materials used in this method are as follows:
——Color-changing silica gel: Dry at 120°C for 2 h;
——Calcium fluoride: Analytical grade;
——High-purity nitrogen: Purity 99.999%;
——Hopcalite oxidizing agent: The main components are 60% manganese oxide (MnO) and 40% copper oxide (CuO), with particles ranging from 830 μm to 1,000 μm. During use and storage, they shall be kept dry;
——Carbon monoxide standard gas (stored in aluminum alloy bottle): Uncertainty < 1%.
4.1.4 Sampling
4.1.4.1 The sampling points shall be distributed in accordance with the provisions of Annex A.
4.1.4.2 The instrument can be used to measure carbon monoxide in the air directly on the spot; it can also use plastic aluminum foil composite film air collection bag, extract the air on the spot to rinse 3~4 times, collect 0.5 L or 1.0 L, seal the air inlet, and bring it back to the laboratory for analysis.
4.1.5 Analysis steps
4.1.5.1 Instrument zero point calibration: After the power supply is turned on and the instrument is stable, connect high-purity nitrogen or air after passing through Hopcalite oxidation pipe and drying pipe into the air inlet of the instrument for zero point calibration.
4.1.5.2 Instrument endpoint calibration: Carbon monoxide standard gas is connected to the sample inlet of the instrument, and the endpoint scale calibration is carried out.
4.1.5.3 Repeat the zero point and end point calibration 2 ~ 3 times to keep the instrument in normal working state.
4.1.5.4 Sample determination: The air collection bag containing air sample is connected to the air inlet of the instrument through a filter containing color-changing silica gel or calcium chloride. After drying, the sample is automatically pumped into the air chamber. The instrument displays the carbon monoxide concentration and records it after reading. If the instrument is used in the field, it may directly read the concentration of carbon monoxide in the air.
4.1.6 Calculation of results
4.1.6.1 Concentration conversion: If the instrument concentration reading value is the volume fraction of carbon monoxide, it can be converted into the mass concentration under the standard state using Equation (1).
(1)
where,
ρ——the mass concentration of carbon oxide, mg/m3;
φ——the volume fraction of carbon oxide, mL/m3;
B——the molar volume of gas in standard state (273.15 K, 101.325 kPa), B = 22.4 L/mol;
M——the molar mass of carbon monoxide, M is 28, g/mol.
4.1.6.2
Result expression: The measurement results of an area are given as the arithmetic mean of the mass concentration of each measuring point in the area.
4.1.7 Measurement range and precision
4.1.7.1 The minimum detected mass concentration of this method is 0.125 mg/m3, and the measurement range is 0.5 mg/m3 ~ 50 mg/m3.
4.1.7.2 Within the mass concentration range of 0.5 mg/m3 ~ 50mg/m3, the average relative standard deviation of repeated measurements is within ±2%.
4.1.8 Interference and elimination
4.1.8.1 Non-measured components such as methane, carbon dioxide and water vapor in the air have an influence on the measurement results of this method.
4.1.8.2 The use of gas filtering related technology and multiple reflection air chamber structure can eliminate the interference of non-components to be measured such as methane and carbon dioxide in the air, and the use of drying pipe may remove the interference of water vapor.
4.2 Gas chromatography
4.2.1 Principle
After complete separation of carbon monoxide from other components of air in the chromatographic column, it enters the conversion furnace and reacts with hydrogen gas under the catalytic action of nickel catalyst at 360°C to generate methane, which is measured by a hydrogen flame ionization detector.
4.2.2 Apparatus
The apparatus used in this method are as follows:
——Gas chromatograph: equipped with flame ionization detector;
——Reformer: Controllable temperature of 360°C ± 1°C.
——Syringe: 2 mL, 5 mL, 10 mL, 100 mL, within ±1% of the relative volume error.
——Chromatographic column: A stainless steel tube with a length of 2 m and an inner diameter of 2 mm is filled with TDX-01 carbon molecular sieve, and both ends of the column tube are filled with glass wool; before use, the newly installed chromatographic column shall be aged for 10 h under the conditions of column temperature 150°C, detector temperature 180°C, and hydrogen 60 mL/min.
——Conversion column: A stainless steel tube with a length of 15 cm and an inner diameter of 4 mm is filled with nickel catalyst, and both ends of the column tube are plugged with glass wool. The conversion column is arranged in the reformer, one end is communicated with the chromatographic column, and the other end is connected with the detector. Before use, the conversion column shall be aged for 10 h under the conditions of furnace temperature of 360°C and hydrogen gas flow rate of 60 mL/min. Conversion column aging is performed simultaneously with chromatographic column aging.
4.2.3 Reagents and materials
The reagents and materials used in this method are as follows:
——Carbon molecular sieve: TDX-01, 180 μm ~ 250 μm, as a stationary phase;
——Nickel catalyst: 380 μm ~ 550 μm, when the carbon monoxide content is less than 180 mg/m3 and the carbon dioxide content is less than 0.4%, the conversion rate is greater than 95%;
——Carbon monoxide standard gas (stored in aluminum alloy bottle): Uncertainty ≤ 1%;
——High purity nitrogen: > 99.999%;
——Pure hydrogen: > 99.6%;
——Plastic aluminum foil composite film air collection bag: Volume 400 mL ~ 600 mL.
4.2.4 Sampling
4.2.4.1 The sampling points shall be distributed in accordance with the provisions of Annex A.
4.2.4.2 After extracting on-site air and flushing the air collection bag for 3 ~ 4 times, extract 400 mL ~ 600 mL of air, seal the air inlet, and bring it back to the laboratory for analysis.
4.2.5 Analysis steps
4.2.5.1 Chromatographic analysis conditions: Chromatographic analysis conditions often vary due to different test conditions. The best chromatographic analysis conditions for carbon monoxide analysis shall be determined according to the model and performance of the gas chromatograph used.
Chromatographic analysis reference conditions:
Foreword i
Introduction ii
1 Scope
2 Normative references
3 Terms and definitions
4 Carbon monoxide
5 Carbon dioxide
6 Inhalable particulate matter
7 Fine particulate matter
8 Formaldehyde
9 Ammonia
10 Total volatile organic compounds
11 Benzene, toluene, xylene
12 Ozone
13 Urea
14 Hydrogen sulfide
15 Oxidation-reduction potential
Annex A (Normative) Requirements for on-site sampling and measuring points
Annex B (Normative) Determination of mass concentration conversion coefficient and relative error of total uncertainty
GB/T 18204.2-2025 Examination methods for public places - Part 2: Chemical indicators
1 Scope
This document describes the methods for determining chemical indicators in indoor air of public places, urea and oxidation-reduction potential of swimming pool water.
This document is applicable to the determination of chemical indicators in indoor air of public places, urea and oxidation-reduction potential of swimming pool water. Other places, rooms and other indoor environments shall be implemented with reference.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies..
GB/T 11742 Standard method for hygienic examination of hydrogen sulfide in air of residential areas - Methylene blue spectrophotometric method
GB/T 14669 Air quality - Determination of ammonia - Ion selective electrode method
GB/T 16129 Standard method for hygienic examination of formaldehyde in air of residential areas - Spectrophotometric method
GB/T 18883 Indoor air quality standard
HJ 590-2010 Ambient air - Determination of ozone - Ultraviolet photometric method
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
standard state
air state at a temperature of 0°C (or absolute temperature of 273.15 K) and an atmospheric pressure of 101.325 kPa
4 Carbon monoxide
4.1 Non-dispersive infrared analysis method
4.1.1 Principle
Carbon monoxide (CO) selectively absorbs infrared rays. Within a certain range, the absorption value is linearly related to the concentration of carbon monoxide, and the concentration of carbon monoxide in the sample may be determined based on the absorption value.
4.1.2 Apparatus
The indicators of the non-dispersive infrared carbon monoxide gas analyzer used for measurement are as follows:
——Measuring range: 0.125 mg/m3 ~ 62.5 mg/m3;
——Reproducibility: within ±1% full scale;
——Zero drift: within ±2% full scale/h;
——Range drift: within ±2% full scale/3h;
——Linear deviation: within ±2% full scale;
——Response time: t90%<45 s.
4.1.3 Reagents and materials
The reagents and materials used in this method are as follows:
——Color-changing silica gel: Dry at 120°C for 2 h;
——Calcium fluoride: Analytical grade;
——High-purity nitrogen: Purity 99.999%;
——Hopcalite oxidizing agent: The main components are 60% manganese oxide (MnO) and 40% copper oxide (CuO), with particles ranging from 830 μm to 1,000 μm. During use and storage, they shall be kept dry;
——Carbon monoxide standard gas (stored in aluminum alloy bottle): Uncertainty < 1%.
4.1.4 Sampling
4.1.4.1 The sampling points shall be distributed in accordance with the provisions of Annex A.
4.1.4.2 The instrument can be used to measure carbon monoxide in the air directly on the spot; it can also use plastic aluminum foil composite film air collection bag, extract the air on the spot to rinse 3~4 times, collect 0.5 L or 1.0 L, seal the air inlet, and bring it back to the laboratory for analysis.
4.1.5 Analysis steps
4.1.5.1 Instrument zero point calibration: After the power supply is turned on and the instrument is stable, connect high-purity nitrogen or air after passing through Hopcalite oxidation pipe and drying pipe into the air inlet of the instrument for zero point calibration.
4.1.5.2 Instrument endpoint calibration: Carbon monoxide standard gas is connected to the sample inlet of the instrument, and the endpoint scale calibration is carried out.
4.1.5.3 Repeat the zero point and end point calibration 2 ~ 3 times to keep the instrument in normal working state.
4.1.5.4 Sample determination: The air collection bag containing air sample is connected to the air inlet of the instrument through a filter containing color-changing silica gel or calcium chloride. After drying, the sample is automatically pumped into the air chamber. The instrument displays the carbon monoxide concentration and records it after reading. If the instrument is used in the field, it may directly read the concentration of carbon monoxide in the air.
4.1.6 Calculation of results
4.1.6.1 Concentration conversion: If the instrument concentration reading value is the volume fraction of carbon monoxide, it can be converted into the mass concentration under the standard state using Equation (1).
(1)
where,
ρ——the mass concentration of carbon oxide, mg/m3;
φ——the volume fraction of carbon oxide, mL/m3;
B——the molar volume of gas in standard state (273.15 K, 101.325 kPa), B = 22.4 L/mol;
M——the molar mass of carbon monoxide, M is 28, g/mol.
4.1.6.2
Result expression: The measurement results of an area are given as the arithmetic mean of the mass concentration of each measuring point in the area.
4.1.7 Measurement range and precision
4.1.7.1 The minimum detected mass concentration of this method is 0.125 mg/m3, and the measurement range is 0.5 mg/m3 ~ 50 mg/m3.
4.1.7.2 Within the mass concentration range of 0.5 mg/m3 ~ 50mg/m3, the average relative standard deviation of repeated measurements is within ±2%.
4.1.8 Interference and elimination
4.1.8.1 Non-measured components such as methane, carbon dioxide and water vapor in the air have an influence on the measurement results of this method.
4.1.8.2 The use of gas filtering related technology and multiple reflection air chamber structure can eliminate the interference of non-components to be measured such as methane and carbon dioxide in the air, and the use of drying pipe may remove the interference of water vapor.
4.2 Gas chromatography
4.2.1 Principle
After complete separation of carbon monoxide from other components of air in the chromatographic column, it enters the conversion furnace and reacts with hydrogen gas under the catalytic action of nickel catalyst at 360°C to generate methane, which is measured by a hydrogen flame ionization detector.
4.2.2 Apparatus
The apparatus used in this method are as follows:
——Gas chromatograph: equipped with flame ionization detector;
——Reformer: Controllable temperature of 360°C ± 1°C.
——Syringe: 2 mL, 5 mL, 10 mL, 100 mL, within ±1% of the relative volume error.
——Chromatographic column: A stainless steel tube with a length of 2 m and an inner diameter of 2 mm is filled with TDX-01 carbon molecular sieve, and both ends of the column tube are filled with glass wool; before use, the newly installed chromatographic column shall be aged for 10 h under the conditions of column temperature 150°C, detector temperature 180°C, and hydrogen 60 mL/min.
——Conversion column: A stainless steel tube with a length of 15 cm and an inner diameter of 4 mm is filled with nickel catalyst, and both ends of the column tube are plugged with glass wool. The conversion column is arranged in the reformer, one end is communicated with the chromatographic column, and the other end is connected with the detector. Before use, the conversion column shall be aged for 10 h under the conditions of furnace temperature of 360°C and hydrogen gas flow rate of 60 mL/min. Conversion column aging is performed simultaneously with chromatographic column aging.
4.2.3 Reagents and materials
The reagents and materials used in this method are as follows:
——Carbon molecular sieve: TDX-01, 180 μm ~ 250 μm, as a stationary phase;
——Nickel catalyst: 380 μm ~ 550 μm, when the carbon monoxide content is less than 180 mg/m3 and the carbon dioxide content is less than 0.4%, the conversion rate is greater than 95%;
——Carbon monoxide standard gas (stored in aluminum alloy bottle): Uncertainty ≤ 1%;
——High purity nitrogen: > 99.999%;
——Pure hydrogen: > 99.6%;
——Plastic aluminum foil composite film air collection bag: Volume 400 mL ~ 600 mL.
4.2.4 Sampling
4.2.4.1 The sampling points shall be distributed in accordance with the provisions of Annex A.
4.2.4.2 After extracting on-site air and flushing the air collection bag for 3 ~ 4 times, extract 400 mL ~ 600 mL of air, seal the air inlet, and bring it back to the laboratory for analysis.
4.2.5 Analysis steps
4.2.5.1 Chromatographic analysis conditions: Chromatographic analysis conditions often vary due to different test conditions. The best chromatographic analysis conditions for carbon monoxide analysis shall be determined according to the model and performance of the gas chromatograph used.
Chromatographic analysis reference conditions:
Contents of GB/T 18204.2-2025
Foreword i
Introduction ii
1 Scope
2 Normative references
3 Terms and definitions
4 Carbon monoxide
5 Carbon dioxide
6 Inhalable particulate matter
7 Fine particulate matter
8 Formaldehyde
9 Ammonia
10 Total volatile organic compounds
11 Benzene, toluene, xylene
12 Ozone
13 Urea
14 Hydrogen sulfide
15 Oxidation-reduction potential
Annex A (Normative) Requirements for on-site sampling and measuring points
Annex B (Normative) Determination of mass concentration conversion coefficient and relative error of total uncertainty
