Some standard content:
National Standard of the People's Republic of China
Health standard for trichlormethane in the air of workplace
1 Subject content and scope of application
This standard specifies the maximum allowable concentration of trichloromethane in the air of workplace and the monitoring and inspection methods. This standard is applicable to all types of enterprises that produce and use trichloromethane. 2 Hygiene requirements
The maximum allowable concentration of trichloromethane in workplace air is 20mg/m. Monitoring and inspection methods
The concentration of trichloromethane in workplace air is determined by gas chromatography, see Appendix A (supplement). Approved by the State Administration of Technical Supervision on April 3, 1996 486
GB 16219—1996
Implemented on September 1, 1996
A1 Polyethylene glycol 6000 column (direct injection) A1.1 Principle
GB16219-1996
Appendix A
Gas chromatography
(Supplement)
Chloroform in air is separated by polyethylene glycol 6000 column and detected by hydrogen flame ionization detector. Retention time is used for qualitative analysis and peak height is used for quantitative analysis.
A1.2 Instruments
A1.2.1 Syringe, 100 mL, 2 mL.
A1.2.2 Micro syringe, 10 μL, 1 μL. A1.2.3 Gas chromatograph, hydrogen flame ionization detector. The signal-to-noise ratio given by 80ng chloroform is not less than 3:1. Chromatographic column: 2 m long, 4 mm inner diameter, stainless steel column. Polyethylene glycol 6000 column: 6201 support 5:100 column temperature: 90°C
vaporization chamber temperature: 120°C.
detection chamber temperature: 150°C.
carrier gas (nitrogen): 25mL/min.
A1.3 Reagents
A1.3.1 Chloroform, chromatographic grade.
A1.3.2 Polyethylene glycol 6000, chromatographic stationary phase. A1.3.36201 red support, 60~80 mesh. A1.4 Sampling
Use a 100mL syringe to draw air at the sampling site for three times, then draw 100mL of air, put a rubber cap on the syringe, place it vertically, and analyze it on the same day.
A1.5 Analysis steps
A1.5.1 Control test: Use a 100mL syringe to draw 100mL of clean air, analyze it at the same time as the sample, as a control. A1.5.2 Sample treatment: Place the sample and control sample syringes vertically, and record the temperature and air pressure in the laboratory. A1.5.3 Standard curve drawing: Use a micro syringe to draw a certain amount of chloroform (at 15℃, the mass of 1μL chloroform is 1.4916 mg) and inject it into a 100mL syringe to prepare a certain concentration of chloroform concentrated standard gas. Take a certain amount of chloroform concentrated standard gas and dilute it with air to 0.12, 0.24, 0.48 and 1.20μg/mL chloroform standard gas. Take 1mL for injection. Repeat three times for each concentration, take the average value of the peak height, plot the chloroform content against the peak height, and draw a standard curve. Qualitative analysis by retention time. A1.5.4 Determination: Take 1 mL of air sample and inject directly, qualitative analysis by retention time, quantitative analysis by peak height. 487
A1.6 Calculation
GB 16219-1996
Trifluoromethane
Carbon tetrafluoride
Time, min
Figure A1 Chromatogram of chloroform
Where: X--Chloroform concentration in air, mg/m;V. - Sample volume under standard conditions, mLX 1000
C--Trifluoromethane content found on the standard curve, μg. A1.7 Explanation
A1.7.1 The detection limit of this method is 8×10-2μg. *(A1)
A1.7.2 This method is to determine the instantaneous concentration of chloroform in the workshop air. In order to comprehensively evaluate the workshop air quality, the sampling frequency should be increased. A1.7.3 The storage time of the sample after sampling shall not exceed 24 hours, otherwise the content will change. During the transportation and storage of the sample, the syringe should be placed vertically.
A1.7.4 The clean air used to prepare the standard gas and the control sample refers to the air without chloroform or other interfering substances. A1.7.5 The separation effect can be improved by changing the chromatographic operating conditions to eliminate the interference of other chemical substances. A2FFAP column (carbon disulfide desorption injection) A2.1 Principle
Chloroform (chloroform) in the air is adsorbed by activated carbon and desorbed by carbon disulfide. After the desorbed liquid is separated by the FFAP column, it is detected by the hydrogen flame ionization detector, and the retention time is used for qualitative analysis and the peak height is used for quantitative analysis. A2.2 Instrument
A2.2.1 Activated carbon sampling tube.
A2.2.2 Sampling pump, 0~11/min.
GB16219—1996
A2.2.3 Micro syringe, 100μL, 10μL, 1μL. A2.2.4 Stoppered test tube, 5mL.
A2.2.5 Gas chromatograph, hydrogen flame ionization detector, the signal-to-noise ratio given by 928ng chloroform is not less than 3:1. Chromatographic column: column length 2m, inner diameter 4mm, stainless steel column. FFAP: 6201 support = 10:100bzxz.net
Column temperature: 90℃
Vaporization chamber temperature: 150℃.
Detection chamber temperature: 150℃.
Carrier gas (nitrogen): 25mL/min.
A2.3 Reagents
A2.3.1 Chloroform, chromatographic grade.
A2.3.2 FFAP, chromatographic stationary liquid.
A2.3.36201 Red carrier, 60-80 mesh. A2.3.4 Carbon disulfide, analytical grade, no impurity peaks in chromatographic identification. A2.4 Sampling
At the sampling site, gently cut the two ends of the carbon tube with a grinding wheel, connect the air outlet to the sampler and place it vertically, extract 12I of air at a rate of 1.0L/min, then plug the original cap and bring it back to the laboratory for analysis. A2.5 Analysis steps
A2.5.1 Control experiment: Take another activated carbon tube and analyze it at the same time as the sample without sampling on site as a control. A2.5.2 Sample treatment: Pour the first and last two sections of activated carbon into stoppered test tubes respectively, add 1 mL of carbon disulfide to each, immediately add stoppers and shake for 1 min, and analyze after standing for 30 min.
A2.5.3 Standard curve drawing: Add a small amount of carbon disulfide to a 25 mL volumetric flask and weigh it. Use a micro syringe to extract an appropriate amount of chloroform (at 15°C, the mass of 1 μl of chloroform is 1.4916 mg) and inject it into the volumetric flask. After weighing for the second time, add carbon disulfide to the scale to prepare a chloroform standard stock solution. When used, dilute with carbon disulfide to 0.3, 0.6 and 1.2 mg/mL standard application solution, and take 2 μL for injection. Repeat each concentration three times, take the average value of the peak height, plot the chloroform content against the average peak height, and draw a standard curve. Qualitative analysis is based on retention time.
A2.5.4 Determination: Take 2μL of the desorption liquid treated in A2.5.2 and inject it, and quantify it by peak height. 189
A2.6 Calculation
GB16219—1996
Trifluoromethane
Carbon monosulfide
Time, min
Figure A2 Chromatogram of desorption of trifluoromethane by carbon disulfide C
X= v.%× 500
Where: X--trifluoromethane concentration in air, mg/m~;V. —Sample volume under standard conditions, L; C--trifluoromethane content found on the standard curve, μg; D--desorption efficiency, %.
A2.7 Explanation
A2.7.1 This method can determine the average concentration of chloroform in workshop air, and the detection limit of the method is 9.3×10-2μg. A2.7.2 The penetration capacity of chloroform in this method is 10.0mg. A2.7.3 The average desorption efficiency of carbon disulfide is 93.4% when it is used as desorbent. A2.7.4 The activated carbon tube after sampling can be stored vertically at room temperature for one week, and its desorption efficiency is still not less than 93.4%. A2.7.5 The separation effect can be improved by changing the chromatographic operating conditions to eliminate the interference of other chemical substances. Additional notes:
This standard was proposed by the Ministry of Health of the People's Republic of China. This standard was drafted by Shanghai Medical University. The main drafters of this standard are Jiang Xuezhi, Liang Youxin and Li Linghong. This standard is interpreted by the Institute of Labor Hygiene and Occupational Diseases, Chinese Academy of Preventive Medicine, which is the technical management unit entrusted by the Ministry of Health. 490
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