This standard specifies the maximum permissible concentration of chloromethane in workshop air and its monitoring and inspection methods. This standard is applicable to all types of enterprises that produce and use chloromethane. GB 16192-1996 Hygienic Standard for Chloromethane in Workshop Air GB16192-1996 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Health standard for methyl chloride in the air of workplace
1 Subject content and scope of application
This standard specifies the maximum allowable concentration of methyl chloride in the air of workplace and its monitoring and inspection methods. This standard is applicable to all types of enterprises that produce and use methyl chloride. 2 Hygiene requirements
The maximum allowable concentration of methyl chloride in the air of workplace is 40mg/m3. 3 Monitoring and inspection methods
The monitoring and inspection methods of this standard adopt gas chromatography, see Appendix A. Supervision and implementation
Health administrative departments at all levels are responsible for supervising the implementation of this standard. Approved by the State Administration of Technical Supervision on April 3, 1996 110
GB16192—1996
Implementation on September 1, 1996
A1 Principlebzxz.net
GB 16192—1996
Appendix A
Gas chromatography
(Supplement)
When chloromethane and dichloromethane coexist in the air, they are separated by dichlorophthalate column and detected by hydrogen flame ionization detector. Retention time is qualitative and peak height is quantitative.
The detection limit of this method is 2.7×10'μg (direct injection of 1mL air sample). A2 Apparatus
A2.1 Syringe: 100ml, 20ml, 2ml. A2.2 Micro syringe: 50μl.
A2.3 Gas chromatograph: hydrogen flame ionization detector. A3 Reagents
A3.1 Methyl chloride, purity above 98%.
A3.2 Dinonyl phthalate, chromatographic stationary liquid. A3.3 102 carrier, 60-80 mesh.
A4 Sampling
Use a 100mL syringe to draw and wash with on-site air three times at the sampling site, then extract 100mL of on-site air sample, put on a rubber cap, store vertically, and analyze on the same day.
A5 Analysis steps
A5.1 Chromatographic conditions
Chromatographic column: 2m long, 4mm inner diameter, stainless steel column. Dinonyl phthalate: 102 carrier = 15:100. a.
Column temperature: 45℃.
Detection room temperature: 90℃.
Vaporization chamber temperature: 100℃.
e. Carrier gas (nitrogen): 34 ml/min. A5.2 Standard curve drawing
Use a 50μl syringe to accurately take a certain amount of methyl chloride (under standard conditions, the mass of 1mL methyl chloride gas is 2.31mg) and inject it into a 100ml syringe. Use clean air to make a certain concentration of standard gas, and then use a 100mL syringe to appropriately dilute it into 0.02, 0.04, and 0.08μg/ml. of methyl chloride standard gas, take 1mL of injection, measure retention time and peak height, repeat each concentration 3 times, take the average peak height, plot the methyl chloride content against the peak height, and draw a standard curve. The retention time is a qualitative indicator. A5.3 Chromatogram
See Figure Al.
A5.4 Sample analysis
GB16192—1996
Time. min
1—air peak; 2—chloromethane; 3—dichloromethane Take 1mL of air sample (record temperature and pressure) for sampling and analysis. Use retention time for qualitative analysis and peak height for quantitative analysis. A6 Calculation
Where: X-
Concentration of chloromethane in air, mg/m;
Concentration of chloromethane found from the standard curve, ug; Injection volume under standard conditions, mL.
A7 Explanation
A7.1 When the concentration is 40mg/m2, the coefficient of variation of this method is 4.2%. A7.2 Use a large syringe to collect samples, pay attention to the representativeness of the sample, and analyze it as soon as possible, not more than 24h. A7.3 Clean air refers to air that does not contain fluoromethane and its interfering impurities. A7.4 Under the conditions of this method, methane, dichloromethane, chloroform and carbon tetrachloride have no interference with the determination. (Al)
A7.5 Among the coexisting substances on site, methane is an important factor that may affect the determination of chloroform. Therefore, when selecting analytical conditions, the separation of methane and chloroform should be considered.
Additional Notes:
This standard is proposed by the Ministry of Health of the People's Republic of China. This standard is drafted by the Sichuan Provincial Institute of Labor Hygiene and Occupational Disease Prevention and Control. The main drafters of this standard are Wang Zefu, Ding Shouxian, Chen Shunying, Xiang Weijun, and Kang Zhongyu. This standard is interpreted by the Institute of Labor Hygiene and Occupational Diseases of the Chinese Academy of Preventive Medicine, which is the technical management unit entrusted by the Ministry of Health. 112
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