GB 18561-2001 Occupational exposure limit for 1,1,1-trichloroethane in workplace air

This standard specifies the maximum permissible concentration and time-weighted average permissible concentration of 1,1,1-trichloroethane in the air of a workplace and its monitoring and inspection methods. This standard is applicable to all types of enterprises that produce and use 1,1,1-trichloroethane. GB 18561-2001 Occupational exposure limits for 1,1,1-trichloroethane in the air of a workplace GB18561-2001 Standard download decompression password: www.bzxz.net

GB185612001
This standard is formulated for the first time based on toxicological experiments, on-site labor hygiene surveys, occupational epidemiological survey data, and reference to foreign exposure limits. It is a hygienic standard used for workplace environmental monitoring and health supervision. Appendix A of this standard is the appendix of the standard. This standard is proposed by the Ministry of Health of the People's Republic of China. The drafting unit of this standard is: Toxicology Research Space, School of Public Health, West China University of Medical Sciences. The main drafters of this standard are: Liu Yuqing, Lin Fan, Xiong Tinghui, Tu Zhengshu, Tan Ningzhi. This standard is entrusted to the Institute of Labor Hygiene and Occupational Diseases, Chinese Academy of Preventive Medicine for interpretation. 728
National Standard of the People's Republic of China
1,1,1-trichloroethane in the air of workplace
Occupational exposure limit for1,1.1-trichloroethanein the air of workplace
GB18561—2001
This standard specifies the maximum permissible concentration and time-weighted average permissible concentration of 1,1,1-dichloroethane in the air of workplace and its monitoring and inspection methods.
This standard is applicable to all types of enterprises producing and using 1,1,1-trifluoroethane. 2 Hygiene requirements
The maximum allowable concentration of 1,1,1-trichloroethane in workshop air is 1 200 rmg/rm, and the time-weighted average allowable concentration is 900 mg/m. 3 Monitoring and inspection methods
The monitoring and inspection methods of this standard adopt gas chromatography, see Appendix A (Record of the standard)) Approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on December 4, 2001 and implemented on May 1, 2002
A1 Principle
GB 18561--2001
Appendix A
(Appendix of the standard)
1,1,1-Trifluoroethane in workshop air Gas chromatography method 1,1,1-Trichloroethane (TCE) in the air is collected with activated carbon, desorbed with carbon disulfide, separated by FFAP column, and detected by hydrogen flame ionization detector. The retention time is used for qualitative analysis and the height is used for quantitative analysis. A2 Instruments
A2. 1 Activated carbon tube: Solvent decomposition type, containing 100/50 mg activated carbon. A2.2 Air sampler; flow rate 0~1 L/min, A2. 3 Micro syringe: 100 μL, 10 μL, 1 μl. A2.4 Stoppered test tube: 5 ml
A2.5 Gas chromatograph, nitrogen-baked ionization detector. Chromatographic column: 2 m long, 4 mm inner diameter stainless steel column. FFAP column; 6201 red support = 10 100. Column temperature: 70℃.
Vaporization chamber temperature: 150℃,
Detection chamber temperature: 150℃,
Carrier gas (nitrogen) flow rate, 25 mL/min.
A3 Reagents
A3.1 1,1-Trichloroethane (TCE): chromatographic grade. A3.2 FFAP; Chromatographic stationary liquid.
A3.36201 Red carrier: 60~80 days.
A3.4 Carbon disulfide: Chromatographic identification shows no impurity peaks. A3.5 TCE standard solution: Add a small amount of carbon disulfide to a 25mL volumetric flask and weigh it accurately. Use a micro-syringe to extract an appropriate amount of TCE (at 20°C, 1μI.TCE has a mass of 1.018mg) and inject it into the volumetric flask. After accurate weighing, add carbon disulfide to the scale. This solution is the TCE standard solution.
A4 Sampling
A4.1 Fixed-point sampling: At the sampling point, open both ends of the activated carbon tube (A2.1), with the orifice at least 2mm, connect the 50mg activated carbon end to the air sampler (A2.2), and place it vertically. Draw 5L of air sample at a flow rate of 0.5L./min. A4.2 Individual sampling: At the sampling point, open both ends of the activated carbon tube (A2.1) with an opening of at least 2mm, connect the 50mg activated carbon end to the air sampler (A2.2), wear it on the upper chest of the monitored person, and collect air samples for 2~8h at a flow rate of 20~50ml./min. After sampling, immediately seal both ends of the activated carbon tube with plastic caps and place it in a clean container for transportation and storage. A5 Analysis steps
A5.1 Control test: Bring the activated carbon tube (A2.1) to the sampling point, except for not collecting air samples, the rest of the operations are the same as the sample, as a blank control of the sample. Www.bzxZ.net
A5.2 Sample treatment: Pour the two sections of activated carbon into the stoppered test tube (A2.4) respectively, add 1.0 mL of carbon disulfide to each, immediately add the stopper and shake at 730°C for 1 minute, place for 30 minutes, and then measure. If the TCE concentration in the desorbed liquid exceeds the measurement range, it can be diluted with carbon disulfide and then measured. When calculating, multiply the dilution multiple.
A5.3 Standard curve drawing: Dilute the standard solution with carbon disulfide to form a standard series of 1.50, 3.00 and 6.00 mg/mL, adjust the gas chromatograph to the best operating conditions, and take 2uL for injection. Repeat each concentration 3 times, take the average value of the peak height and TCE concentration (mg/mL) to draw a standard curve, and the retention time is a qualitative indicator. A5.4 Sample determination: Use the operating conditions of the standard series to determine the sample desorption solution and the blank control desorption solution. After subtracting the blank control peak height from the measured sample peak height, the TCE concentration (mg/mI) is obtained from the standard curve. A6 Calculation
A6. 1 Convert the sampling volume to the volume under standard conditions according to formula (A1): V,=-VX
Where V.—
-converted to the sampling volume under standard conditions, L; V——sampling volume, I
air temperature at the sampling point, ℃:
air pressure at the sampling point, kPa.
A6.2 Calculate the concentration of TCE in the air according to formula (A2): C
Concentration of TCE in the air, mg/m%
Wherein:
Converted to the sampling volume under standard conditions, L; 273
273 + t
×1000
TCE concentration in the desorption solution found from the standard curve, mg/mL: desorption efficiency.
Trifluoroethylene brown
Dinuclear plate
Time. min
Figure Chromatogram of TCE desorption from carbon disulfide
（A2）
A7 Explanation
GB18561—2001
A7:1 The detection limit of this method is 28 g/rnL; the minimum detection concentration is 10 mg/m (based on the collection of 3 air samples). When the TCE concentration is 950, 1900 and 3000 mg/m2, the relative standard deviations are 4.8%, 4.4% and 3.9% respectively. A7.2 The penetration capacity of this method is 31.9 mg. A7.3 The average desorption efficiency of carbon disulfide is 99.2% when used as a desorbent. A7.4 The activated carbon tube after sampling can be placed vertically at room temperature for 2 weeks, and its average recovery rate is not less than 99.1%. A7.5 When other interfering substances that may exist on site have the same retention time as TCE and interfere with the determination of TCE, the chromatographic operating conditions can be changed to eliminate them.
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