GB 18548-2001 Occupational exposure limits for dichlorobenzene in workplace air

This standard specifies the maximum permissible concentration and time-weighted average permissible concentration of dichlorobenzene in workplace air and its monitoring and inspection methods. This standard is applicable to all types of industrial enterprises that produce and use dichlorobenzene. GB 18548-2001 Occupational exposure limits for dichlorobenzene in workplace air GB18548-2001 Standard download decompression password: www.bzxz.net

B18548-2001
This standard is formulated for the first time based on toxicological experiments, on-site labor hygiene surveys, epidemiological survey data and reference to foreign occupational exposure limits. It is a hygienic standard used for workplace environmental monitoring and health supervision. This standard shall be implemented from May 1, 2002. 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 units of this standard are: Institute of Labor Hygiene and Occupational Diseases, Chinese Academy of Preventive Medicine, School of Public Health, Sun Yat-sen University of Medical Sciences, and Tianjin Institute of Labor Hygiene and Occupational Diseases.
The main drafters of this standard are: Zeng Zhaohui, Lü Boqin, He Yuying, and Xu Jia. This standard is entrusted to the Institute of Labor Hygiene and Occupational Diseases, Chinese Academy of Preventive Medicine for interpretation. 259
1 Scope
National Standard of the People's Republic of China
Occupational exposure limit for dichlorobenzene in the air of workplace
GB 18548—2001
This standard specifies the maximum permissible concentration and time-weighted average permissible concentration of dichlorobenzene in the air of workplace and its monitoring and inspection methods. This standard is applicable to all types of industrial enterprises that produce and use dichlorobenzene. 2 Hygiene requirements
The maximum permissible concentration of p-dichlorobenzene in the air of workplace is 60mg/m2 and the time-weighted average permissible concentration is 30mg/m. The maximum permissible concentration of o-dichlorobenzene in the air of workplace is 100mg/m2 and the time-weighted average permissible concentration is 50mg/m. 3 Monitoring and inspection methods
The monitoring and inspection methods of this standard adopt gas chromatography, see Appendix A (Appendix to the standard). Approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on December 4, 2001 260
Implemented on May 1, 2002
A1 Principle
GB18548---2001
Appendix A
(Appendix to the standard)
Gas chromatography method for determination of dichlorobenzene in workshop air Dichlorobenzene in the air is collected by activated carbon tube, desorbed and injected by carbon disulfide, separated by FFAP column, and detected by hydrogen flame ionization detector. Qualitative determination is based on retention time and quantitative determination is based on peak height.
A2 Instruments
A2.1 Activated carbon tube: solvent desorption type.
A2.2 Air sampler: 0~1L/min.
A2.3 Solvent desorption tube: 2mL.
A2.4 Volumetric flask: 1ml, 10mL.
A2.5 Micro-injector: 100μL, 10μL. A2.6 Gas chromatograph, hydrogen flame ionization detector. Chromatographic column: 3m long, 4mm inner diameter, stainless steel column. FFAP: ChromosorbWAW-DMCS=1o:100. Column temperature: 140℃.
Carrier gas (nitrogen) flow rate: 50mL/min. Vaporization chamber temperature: 225℃, detection chamber temperature: 250℃. A3 Reagents
A3.1FFAP: chromatographic stationary liquid.
A3.2ChromosorbWAWDMCS support: 60~80 mesh. A3.3 Carbon disulfide: no impurity interference peak. A3.4 Dichlorobenzene standard push solution: Accurately weigh p-dichlorobenzene (chromatographic grade) and/or o-diazobenzene (chromatographic grade), dissolve in acetone, and prepare 200 mg/ml. p-dichlorobenzene and/or 200 mg/ml. o-dichlorobenzene standard stock solution. Store in refrigerator. Dilute with carbon disulfide to 20 mg/mL standard solution before use.
A4 Sampling
A4.1 Fixed-point sampling: Open the activated carbon tube at the sampling point, place it vertically, and extract 2L of air at a flow rate of 0.2L/min. After sampling, put plastic caps on both ends of the tube and bring it back to the laboratory for analysis. A4.2 Individual sampling: Connect the activated carbon tube to the air sampler, wear it on the monitored person, and keep the air inlet as close to the breathing belt as possible. Sampling at a flow rate of 20-50ml./min for 2-8 hours. After sampling, put plastic caps on both ends of the tube and bring it back to the laboratory for analysis. A5 Analysis steps
A5.1 Control experiment: Bring the activated carbon tube to the sampling point, except for not collecting air, the rest of the operation is the same as the sample, as a blank control of the sample. A5.2 Sample treatment: Pour the activated carbon into the solvent desorption tube, add 1.0ml carbon disulfide, desorb for 30min, and shake from time to time. A5.3 Drawing of standard curve: Dilute the dichlorobenzene standard solution with carbon disulfide to a standard series of 25.0100.0, 200.0ug/mL, take 3μl respectively, inject, measure the retention time and peak height (or peak area), repeat each concentration 3 times, and use the mean peak height (or peak area) to draw the standard curve for the concentration of ortho-dichlorobenzene (μg/mL). 261
GB 18548—2001
A5.4 Sample determination: According to the determination conditions of the standard curve, take 3L of sample desorption solution and blank control desorption solution for sampling and determination. After subtracting the blank control measured value from the sample measured value, check the standard curve to obtain the concentration of para- and/or o-dichlorobenzene (u/mL). Retention time is a qualitative indicator.
A6 Calculation
A6.1 Convert the volume of collected air into the volume under standard conditions according to formula (A1). V. = V, × 273+, × 101.3
Wherein, V. — converted to the sampling volume under standard conditions, LV, — sampling volume at and pressure, L
t—— air temperature at the sampling point, C
p— atmospheric pressure at the sampling point, kPa.
A6.2 Calculate the concentration of dichlorobenzene in the air according to formula (A2). C
Wu Zhong: C
Concentration of p-(or o-)dichlorobenzene in air, mg/m; measured concentration of p-(or o-)dichlorobenzene in carbon disulfide desorption solution, ug/mL; volume of desorption solution, ml
V.--converted to the sampling volume under standard conditions, D---desorption efficiency. bzxZ.net
A7 Explanation
++++(Al)
A7.1 The detection limits of p- and o-dichlorobenzene are 2×10\2 and 1.2×10-2g respectively (3L injection); the minimum detection concentration is 3.3mg/L and 2mg/L (21. air sampling).
A7.2 When the concentration of p- and o-dichlorobenzene is 25~200mg/m2, the relative standard deviation is 1.4%-4.6%. A7.3 The sampling efficiency of 100mg activated carbon sampling tube is 100%; the desorption rates of carbon disulfide are 91.2% and 88.7% respectively. A7.4 The sample can be stored for at least three weeks at room temperature. A7.5 The penetration capacity of p- and o-dichlorobenzene is >28.6mg/100mg and 20mg/100mg activated carbon respectively. A7.6 Benzene and chlorobenzene do not interfere with the determination.
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