This standard specifies the maximum permissible concentration of dichloromethane in workshop air and its monitoring and inspection methods. This standard is applicable to all types of enterprises that produce and use dichloromethane. GB 16218-1996 Hygienic Standard for Dichloromethane in Workshop Air GB16218-1996 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Health standard for dichloromethane in the air of workplace
1 Subject content and scope of application
This standard specifies the maximum allowable concentration of dichloromethane in the air of workplace and its monitoring and inspection methods. This standard is applicable to all types of enterprises that produce and use dichloromethane. 2 Hygiene requirements
The maximum allowable concentration of difluoromethane in workplace air is 200mg/m3. 3 Monitoring and inspection methods
The monitoring and inspection methods of this standard adopt gas chromatography, see Appendix A (supplement). Approved by the State Administration of Technical Supervision on April 3, 1996, GB16218-1996
Implementation on September 1, 1996
A1 Principle
GB16218-1996
Appendix A
Gas chromatographywww.bzxz.net
(Supplement)
When chloromethane and difluoromethane coexist in the air, use dichlorophthalate column to separate, hydrogen flame ionization detector to detect, retention time for qualitative analysis, peak height for quantitative analysis.
A2 Instruments
A2.1 Syringe: 100mL, 1mL.
A2.2 Microsyringe: 0.5μL.
A2.3 Gas chromatograph: hydrogen flame ionization detector. Chromatographic conditions
Chromatographic column: 2m long, 4mm inner diameter, stainless steel column, di-o-phthalate: 102 support 15:100. b.
Column temperature: 50℃.
Detection chamber temperature: 90℃.
Vaporization chamber temperature: 100℃.
Carrier gas (nitrogen): 32mL/min.
A3 Reagents
A3.1 Difluoromethane, chromatographic grade
A3.2 Dinonyl phthalate, chromatographic stationary liquid. A3.3102 support, 60-80 mesh.
A4 Sampling
Use a 100mL syringe to draw and wash with on-site air three times at the sampling site, then draw 100mL of on-site air sample, put on a rubber cap, store vertically, and analyze on the same day.
A5 Analysis steps
A5.1 Control test: Use a 100mL syringe to collect clean air and analyze the same sample. A5.2 Drawing of standard curve: Use a 0.5μL syringe to accurately measure a certain amount of dichloromethane (1μL weighs 1.326mg at 20℃) and use clean air to make a certain concentration of standard gas, then use a 100mL syringe to appropriately dilute and make 0.085, 0.17, 0.34μg/mL dichloromethane standard gas, take 1mL for injection, measure retention time and peak height, repeat 3 times for each concentration, take the average peak height, plot the content against the peak height, draw a standard curve, and use the retention time as a qualitative indicator. The chromatogram is shown in Figure A1.
A5.3 Determination
GB16218-1996
Time, min
1—Air peak; 2—Methylene chloride; 3—Methylene chloride Figure A1 Chromatogram
Take 1mL of air sample for analysis, use retention time for qualitative analysis and peak height for quantitative analysis. A6 Calculation
X 1 000
Where: X-concentration of dichloromethane in air, mg/m; C--—difluoromethane content found from the standard curve, μg; V. —Converted to injection volume under standard conditions, mL. A7 Explanation
(A1)
A7.1 The detection limit of this method is 1.1×10-2μg (direct injection of 1mL air sample). When the concentration is 170mg/m2, the coefficient of variation of this method is 4.1%.
A7.2 This method is used in conjunction with the health standard for dichloromethane. It can also be used for the mixed determination of monofluoromethane and difluoromethane. If it is used for the mixed determination of fluoromethane, other conditions should be selected.
A7.3 Under the conditions of this method, chloroform, chloroform and carbon tetrachloride have no interference with the determination. A7.4 This method is mainly used for on-site determination. In order to adapt to animal experimental determination, due to the short experimental time, single substance and long determination cycle, the analysis temperature will be slightly increased, single-point quantification will be adopted, and the recording paper speed is 5mm/min. Additional remarks:
This standard was proposed by the Ministry of Health of the People's Republic of China. This standard was drafted by the Sichuan Provincial Institute of Labor Hygiene and Occupational Disease Prevention and Control. The main drafters of this standard are Kang Zhongyu, Wang Zefu, Zhang Wanyou, Ding Shouxian and Chen Shunying. 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. 185
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