This standard specifies the determination of methanol and acetone concentrations in residential atmosphere by gas chromatography. This standard applies to the determination of methanol and acetone concentrations in residential atmosphere. GB/T 11737-1989 Standard method for hygienic examination of benzene, toluene and xylene in residential atmosphere Gas chromatography GB/T11737-1989 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Standard method for hygienic examination ofbenzene, toluene and xylene in air ofresidential areas --Gas chromatography
Standard method for hygienic examination ofbenzene, toluene and xylene in air ofresidential areas --Gas chromatography 1 Subject content and scope of application
This standard specifies the determination of the concentration of benzene, toluene and xylene in air ofresidential areas by gas chromatography. GB 11737--89
This standard is applicable to the determination of the concentration of benzene, toluene and xylene in air of residential areas. It is also applicable to the determination of the concentration of benzene, toluene and xylene in indoor air.
1.1 Detection limit
When the sampling volume is 10L, the thermal desorption is 100mL gas sample, and 1mL is injected, the detection limits of benzene, toluene and xylene are 0.005mg/m3, 0.01mg/m2 and 0.02mg/m3 respectively. If 1mL of liquid sample extracted with carbon disulfide is used and 1μL is injected, the detection limits of benzene, toluene and xylene are 0.025mg/m3, 0.05mg/m3 respectively. and 0.1mg/m3. 1.2 Measurement range
When using activated carbon tube to collect gas sample 10L, thermal desorption, the measurement range of benzene is 0.005~10mg/m3, toluene is 0.01~10mg/m3, xylene is 0.02~10mg/m, when carbon disulfide is extracted, the measurement range of benzene is 0.025~~20mg/m2, toluene is 0.05~20mg/m3, xylene is 0.1~20mg/m3.
1.3 Interference and elimination
When the amount of water vapor or water mist in the air is too large, so that it condenses in the carbon tube, it seriously affects the penetration capacity and sampling efficiency of the activated carbon tube. When the air humidity is 90%, the sampling efficiency of the activated carbon tube still meets the requirements. The interference of other pollutants in the air has been eliminated by selecting appropriate chromatographic separation conditions due to the use of gas chromatography separation technology. 2 Principle
Benzene, toluene and xylene in the air are collected with activated carbon tubes, then extracted by thermal desorption or carbon disulfide, separated by polyethylene glycol 6000 chromatographic column, detected by hydrogen flame ionization detector, qualitative by retention time and quantitative by peak height. 3 Reagents and materials
3.1 Benzene: chromatographic grade.
3.2 Toluene: chromatographic grade.
Xylene: chromatographic grade.
Carbon disulfide: analytical grade, needs to be purified, the treatment method is shown in Appendix A (Supplement). 3.5
Chromatographic stationary liquid: polyethylene glycol 6000.
6201 Support: 60-80 mesh.
Coconut shell activated carbon: 20-40 mesh, used to load activated carbon sampling tubes. Pure nitrogen: 99.99%.
Approved by the Ministry of Health of the People's Republic of China on September 21, 1989, and implemented on July 1, 1990
4 Instruments and Equipment
GB11737-89
4.1 Activated carbon sampling tube: Use a glass tube with a length of 150mm, an inner diameter of 3.5~4.0mm, and an outer diameter of 6mm, and fill it with 100mg coconut shell activated carbon, and fix both ends with a small amount of glass wool. After the tube is installed, blow it with pure nitrogen at a temperature of 300~350℃ for 5~10min, and then put on a plastic cap to seal both ends of the tube. This tube can be stored in a desiccator for 5 days. If the glass tube is melt-sealed, this tube can be stable for three months. 4.2 Air sampler
Flow range 0.2~1L/min, stable flow. When using, use a soap film flowmeter to calibrate the flow of the sampling series before and after sampling. The flow error should be less than 5%.
4.3 Syringe: 1mL, 100mL. The volume scale error should be corrected. 4.4 Microsyringe: 1μL, 10μL. The volume scale error should be corrected. 4.5 Thermal desorption device: The thermal desorption device is mainly composed of a heater, a temperature controller, a temperature gauge and a gas flow controller. The temperature adjustment range is 100400℃, the temperature control accuracy is ±1℃, the thermal desorption gas is nitrogen, the flow adjustment range is 50～100mL/min, and the reading error is ±1mL/min. The structure of the thermal desorption device used should enable the activated carbon tube to be easily inserted into the heater, and all parts should be heated evenly.
4.6 Stoppered graduated test tube: 2ml. Www.bzxZ.net
4.7 Gas chromatograph: with hydrogen flame ionization detector. 4.8 Chromatographic column: 2m long, 4mm inner diameter stainless steel column, filled with polyethylene glycol 6000-6201 support (5:100) stationary phase. 5 Sampling
Open the activated carbon tube at the sampling site, with the hole diameter of both ends at least 2mm, and connect it vertically to the air sampler inlet, and extract 10L of air at a rate of 0.5L/min. After sampling, put plastic caps on both ends of the tube, and record the temperature and atmospheric pressure at the time of sampling. The sample can be stored for 5 days.
6 Analysis steps
6.1 Chromatographic analysis conditions
Since chromatographic analysis conditions often vary due to different experimental conditions, the best chromatographic analysis conditions for analyzing benzene, toluene and xylene should be formulated according to the model and performance of the gas chromatograph used. The chromatographic analysis conditions listed in Appendix B (reference) are an example. 6.2 Drawing standard curves and determining calculation factors Under the same conditions as the sample analysis, draw standard curves and determine calculation factors. 6.2.1 Drawing a standard curve with mixed standard gas Use a micro syringe to accurately take a certain amount of benzene, toluene and xylene (at 20℃, 1μL of benzene weighs 0.8787mg, toluene weighs 0.8669mg, and o-, m-, and p-xylene weigh 0.8802, 0.8642, and 0.8611mg respectively) and inject them into a 100mL syringe respectively. Use nitrogen as the base gas to prepare a standard gas of a certain concentration. Take a certain amount of benzene, toluene and xylene standard gas and inject them into the same 100mL syringe respectively to mix them, and then use nitrogen to dilute them step by step to form a mixed gas of benzene, toluene and xylene at four concentration points within the range of 0.02-2.0μg/mL. Take 1mL of sample and measure the retention time and peak height. Repeat 3 times for each concentration and take the average peak height. Draw a standard curve with the content of benzene, toluene and xylene (μg!mL) as the horizontal axis and the average peak height (mm) as the vertical axis. And calculate the slope of the regression line, and use the reciprocal of the slope Bg [μg/(mL·mm)] as the calculation factor for sample determination. 6.2.2 Use standard solution to draw standard curve
In 3 50mL volumetric flasks, first add a small amount of carbon disulfide, use a 10μL syringe to accurately measure a certain amount of benzene, toluene and xylene and inject them into the volumetric flasks respectively, add carbon disulfide to the scale, and prepare a stock solution of a certain concentration. Before use, take a certain amount of stock solution and dilute it with carbon disulfide step by step to make a mixed standard solution with benzene, toluene and xylene contents of 0.005, 0.01, 0.05, and 0.2μg/mL. Take 1μL of sample for injection respectively, measure the retention time and peak height, repeat 3 times for each concentration, take the average peak height, and draw the standard curve with the content of benzene, toluene and xylene (μg/μL) as the horizontal axis and the average peak height (mm) as the vertical axis. And calculate the slope of the regression line, and use the reciprocal of the slope Bsμg/(μL·mm) as the calculation factor for sample determination. 146
6.2.3 Determination of correction factor
GB11737—89
When the stability of the instrument is poor, the correction factor can be calculated by the single-point correction method. While the sample is being determined, take 1mL of standard gas or 1μL of standard solution with a concentration close to that of benzene, toluene and xylene in the sample thermal desorption gas (or carbon disulfide extract), respectively, and operate according to 6.2.1 or 6.2.2 to measure the chromatographic peak height (mm) and retention time of the zero concentration and the standard, and calculate the correction factor using formula (1). f
Where:
ho, hs-
6.3 Sample analysis
（1）)
Correction factor, μg/(mL·mm) (for thermal desorption gas sample) or μg/(μL·mm) (for carbon disulfide extract sample),
-Standard gas or standard solution concentration, μg/mL or μg/μLZero concentration, standard average peak height, mm. 6.3.1 Thermal desorption method sampling
Connect the sampled activated carbon tube with a 100mL syringe and place it on the thermal desorption device. Desorb with nitrogen at a rate of 50-60mL/min at 350℃. The desorption volume is 100mL. Take 1mL of desorbed gas into the chromatographic column. Use retention time for qualitative analysis and peak height (mm) for quantitative analysis. Analyze each sample three times and calculate the average peak height. At the same time, take an unsampled activated carbon tube and perform the same operation as the sample tube to determine the average peak height of the blank tube.
6.3.2 Carbon disulfide extraction method injection
Pour the activated carbon into a stoppered graduated test tube and add 1.0mL carbon disulfide, plug the tube tightly, leave it for 1h, and shake it occasionally. Take 1μL into the chromatographic column, use retention time for qualitative analysis and peak height (mm) for quantitative analysis. Each sample is analyzed three times and the average peak height is calculated. At the same time, take an unsampled activated carbon tube and perform the same operation as the sample tube to measure the average peak height (mm) of the blank tube. 7 Result calculation
7.1 Convert the sampling volume into the sampling volume under standard conditions according to formula (2). V. =Vt
273 +t
Where: Vo-converted into the sampling volume under standard conditions, L-sampling volume, L,
T. -—absolute temperature of standard conditions, 273K, t-—temperature of the sampling point during sampling, ℃,-atmospheric pressure of standard conditions, 101.3kPa; Po
—atmospheric pressure of the sampling point during sampling, kPa. p
7.2 When using the thermal desorption method, the concentration of benzene, toluene and xylene in the air is calculated according to formula (3). c
In the formula:
(h-ho)·Bg
—×100
-the concentration of benzene or toluene, xylene in the air, mg/m3, - the average value of the sample peak height, mm,
-the peak height of the blank tube, mm;
the calculation factor obtained from 6.2.1, μg/(mL, mm)Bg-
-the thermal desorption efficiency determined by the experiment.
7.3 When using the carbon disulfide extraction method, the concentration of benzene, toluene and xylene in the air is calculated according to formula (4). C
(h-ho)·Bs
× 1000
V. ·Es
Where: c--concentration of benzene or toluene or xylene, mg/m3, -correction factor obtained from 6.2.2, μg/(μL·mm)3Bs
（2）
（3）
（4）
GB11737--89
Efficiency of carbon disulfide extraction determined by experiment. E.
7.4 When using the correction factor, the concentration of benzene, toluene and xylene in the air is calculated according to formula (5). C =
(h-ho)·f
×100 or c
(h-ho)·f
Vo·Es
Vo·Eg
wherein: f is the correction factor obtained from 6.2.3, mg/(mL·mm) (for thermal desorption samples) or μg/(μL·mm) (for liquid samples extracted with carbon disulfide).
Precision and Accuracy
8.1 Precision
8.1.1 Using the thermal desorption method, the coefficients of variation of repeated measurements of gas samples with benzene concentrations of 0.1, 0.5 and 2.0 μg/mL were 7%, 6% and 4% respectively. The coefficients of variation of repeated measurements of gas samples with toluene concentrations of 0.1, 0.5 and 2.0 μg/mL were 9%, 7% and 4% respectively. The coefficients of variation of repeated measurements of gas samples with xylene concentrations of 0.1, 0.5 and 2.0 μg/mL were 9%, 6% and 5%. 8.1.2 Using the carbon disulfide extraction method, for liquid samples with benzene concentrations of 8.78 and 21.9 μg/mL, the coefficients of variation for repeated measurements were 7% and 5%, for liquid samples with toluene concentrations of 17.3 and 43.3 μg/mL, the coefficients of variation for repeated measurements were 5% and 4%, respectively, and for liquid samples with xylene concentrations of 35.2 and 87.9 μg/mL, the coefficients of variation for repeated measurements were 5% and 7%. 8.2 Accuracy
The recoveries of benzene with contents of 5, 50 and 500 μg by thermal desorption were 96%, 97% and 97% respectively, the recoveries of toluene with contents of 10, 100 and 1000 μg were 90%, 91% and 94% respectively, and the recovery of xylene with contents of 95.5 μg was 82%; the recoveries of benzene with contents of 0.5, 21, 1 and 200 μg by carbon disulfide extraction were 95%, 94% and 91% respectively, the recoveries of toluene with contents of 0.5, 41.6 and 500 μg were 99%, 99% and 93% respectively, and the recoveries of xylene with contents of 0.5, 34.4 and 500 μg were 101%, 100% and 90% respectively. 148
GB 11737—89
Appendix A
Purification method of carbon disulfide
(Supplementary material)
Carbon disulfide is repeatedly extracted with 5% concentrated sulfuric acid formaldehyde solution until the sulfuric acid becomes colorless, and then the carbon disulfide is washed with distilled water until it is neutral, and then dried with anhydrous sodium sulfate, redistilled, and stored in a refrigerator for use. Appendix B
Example of gas chromatography analysis of benzene, toluene and xylene in air (reference material)
B1 Chromatographic conditions
Chromatographic column temperature: 90℃,
B1.2 Detection chamber temperature: 150℃,
Vaporization chamber temperature: 150℃,
Carrier gas: nitrogen, 50mL/min.
B2 Chromatograms operated under the chromatographic conditions of B1 are shown in Figures B1 and B2. 3
Time, min
Figure B1 Chromatogram using thermal desorption method
1-Benzene, 2-Toluene, 3-p-xylene, m-xylene, 4-o-xylene, 5-styrene
Additional instructions:
GB11737-89
Time, min
Figure B2 Chromatogram using carbon disulfide extraction method
1-Carbon disulfide, 2-Benzene, 3-Toluene, 4-p-xylene, m-xylene, 5-o-xylene, 6-styrene
This standard was proposed by the Health Supervision Department of the Ministry of Health. This standard was drafted by the Guangdong Provincial Institute for Occupational Disease Prevention and Control, Hangzhou Municipal Health and Epidemic Prevention Station, Nanjing Municipal Health and Epidemic Prevention Station, and Shenyang Municipal Health and Epidemic Prevention Station.
The main drafters of this standard are Ye Nengquan, Lu Zhanrong, and Tong Yingfang. This standard is interpreted by the Institute of Environmental Health Monitoring, Chinese Academy of Preventive Medicine, which is the technical unit entrusted by the Ministry of Health.For the liquid sample with a concentration of 9 μg/mL, the coefficients of variation of repeated measurements were 7% and 5%, for the liquid sample with a toluene concentration of 17.3 and 43.3 μg/mL, the coefficients of variation of repeated measurements were 5% and 4%, and for the liquid sample with a concentration of xylene of 35.2 and 87.9 μg/mL, the coefficients of variation of repeated measurements were 5% and 7%. 8.2 Accuracy
The recoveries of benzene with contents of 5, 50 and 500 μg by thermal desorption were 96%, 97% and 97% respectively, the recoveries of toluene with contents of 10, 100 and 1000 μg were 90%, 91% and 94% respectively, and the recovery of xylene with contents of 95.5 μg was 82%; the recoveries of benzene with contents of 0.5, 21, 1 and 200 μg by carbon disulfide extraction were 95%, 94% and 91% respectively, the recoveries of toluene with contents of 0.5, 41.6 and 500 μg were 99%, 99% and 93% respectively, and the recoveries of xylene with contents of 0.5, 34.4 and 500 μg were 101%, 100% and 90% respectively. 148
GB 11737—89
Appendix A
Purification method of carbon disulfide
(Supplementary material)
Carbon disulfide is repeatedly extracted with 5% concentrated sulfuric acid formaldehyde solution until the sulfuric acid becomes colorless, and then the carbon disulfide is washed with distilled water until it is neutral, and then dried with anhydrous sodium sulfate, redistilled, and stored in a refrigerator for use. Appendix B
Example of gas chromatography analysis of benzene, toluene and xylene in air (reference material)
B1 Chromatographic conditions
Chromatographic column temperature: 90℃,
B1.2 Detection chamber temperature: 150℃,
Vaporization chamber temperature: 150℃,
Carrier gas: nitrogen, 50mL/min.
B2 Chromatograms operated under the chromatographic conditions of B1 are shown in Figures B1 and B2. 3
Time, min
Figure B1 Chromatogram using thermal desorption method
1-Benzene, 2-Toluene, 3-p-xylene, m-xylene, 4-o-xylene, 5-styrene
Additional instructions:
GB11737-89
Time, min
Figure B2 Chromatogram using carbon disulfide extraction method
1-Carbon disulfide, 2-Benzene, 3-Toluene, 4-p-xylene, m-xylene, 5-o-xylene, 6-styrene
This standard was proposed by the Health Supervision Department of the Ministry of Health. This standard was drafted by the Guangdong Provincial Institute for Occupational Disease Prevention and Control, Hangzhou Municipal Health and Epidemic Prevention Station, Nanjing Municipal Health and Epidemic Prevention Station, and Shenyang Municipal Health and Epidemic Prevention Station.
The main drafters of this standard are Ye Nengquan, Lu Zhanrong, and Tong Yingfang. This standard is interpreted by the Institute of Environmental Health Monitoring, Chinese Academy of Preventive Medicine, which is the technical unit entrusted by the Ministry of Health.For the liquid sample with a concentration of 9 μg/mL, the coefficients of variation of repeated measurements were 7% and 5%, for the liquid sample with a toluene concentration of 17.3 and 43.3 μg/mL, the coefficients of variation of repeated measurements were 5% and 4%, and for the liquid sample with a concentration of xylene of 35.2 and 87.9 μg/mL, the coefficients of variation of repeated measurements were 5% and 7%. 8.2 Accuracy
The recoveries of benzene with contents of 5, 50 and 500 μg by thermal desorption were 96%, 97% and 97% respectively, the recoveries of toluene with contents of 10, 100 and 1000 μg were 90%, 91% and 94% respectively, and the recovery of xylene with contents of 95.5 μg was 82%; the recoveries of benzene with contents of 0.5, 21, 1 and 200 μg by carbon disulfide extraction were 95%, 94% and 91% respectively, the recoveries of toluene with contents of 0.5, 41.6 and 500 μg were 99%, 99% and 93% respectively, and the recoveries of xylene with contents of 0.5, 34.4 and 500 μg were 101%, 100% and 90% respectively. 148
GB 11737—89
Appendix A
Purification method of carbon disulfide
(Supplementary material)
Carbon disulfide is repeatedly extracted with 5% concentrated sulfuric acid formaldehyde solution until the sulfuric acid becomes colorless, and then the carbon disulfide is washed with distilled water until it is neutral, and then dried with anhydrous sodium sulfate, redistilled, and stored in a refrigerator for use. Appendix B
Example of gas chromatography analysis of benzene, toluene and xylene in air (reference material)
B1 Chromatographic conditions
Chromatographic column temperature: 90℃,
B1.2 Detection chamber temperature: 150℃,
Vaporization chamber temperature: 150℃,
Carrier gas: nitrogen, 50mL/min.
B2 Chromatograms operated under the chromatographic conditions of B1 are shown in Figures B1 and B2. 3
Time, min
Figure B1 Chromatogram using thermal desorption method
1-Benzene, 2-Toluene, 3-p-xylene, m-xylene, 4-o-xylene, 5-styrene
Additional instructions:
GB11737-89
Time, min
Figure B2 Chromatogram using carbon disulfide extraction method
1-Carbon disulfide, 2-Benzene, 3-Toluene, 4-p-xylene, m-xylene, 5-o-xylene, 6-styrene
This standard was proposed by the Health Supervision Department of the Ministry of Health. This standard was drafted by the Guangdong Provincial Institute for Occupational Disease Prevention and Control, Hangzhou Municipal Health and Epidemic Prevention Station, Nanjing Municipal Health and Epidemic Prevention Station, and Shenyang Municipal Health and Epidemic Prevention Station.
The main drafters of this standard are Ye Nengquan, Lu Zhanrong, and Tong Yingfang. This standard is interpreted by the Institute of Environmental Health Monitoring, Chinese Academy of Preventive Medicine, which is the technical unit entrusted by the Ministry of Health.
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