This standard specifies the maximum permissible concentration of maleic anhydride in the air of a workplace, the time-weighted average permissible concentration and its monitoring and testing methods. This standard is applicable to all types of industrial enterprises that produce and use maleic anhydride. GB 18537-2001 Occupational exposure limits for maleic anhydride in the air of a workplace GB18537-2001 Standard download decompression password: www.bzxz.net

GB18537--2001
This standard is formulated for the first time based on on-site labor health surveys, foreign toxicology research data and reference to the exposure limits of major national workplaces. It is a health standard used for workplace environmental monitoring and health supervision. This standard will 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 unit of this standard: Shanxi Labor Health and Occupational Disease Prevention and Control Research Institute. The main drafters of this standard: Wang Jinshan, Liang Quancheng, Li Tong, Geng Jintao, Cao Hongbing. This standard is entrusted to the Institute of Labor Health and Occupational Diseases of the Chinese Academy of Preventive Medicine for interpretation. 648
1 Scope
National Standard of the People's Republic of China
Occupational exposure limit for maleic anhydride in the air of workplace
GB185372001
This standard specifies the maximum permissible concentration, time-weighted average permissible concentration and monitoring and inspection methods of maleic anhydride in the air of workplace. This standard is applicable to industrial enterprises that produce and use maleic anhydride. 2 Hygiene requirements
The maximum permissible concentration of maleic anhydride in the air of workplace is 2.0 mg/m2, and the time-weighted average permissible concentration of maleic anhydride in the air at noon is 1.0 mg/m2.
Monitoring and inspection methods
The monitoring and inspection methods of this standard use liquid 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-rrKAoNrKAca-
Implementation on May 1, 2002
A1 Principle
GB18537-2001
(Appendix to the standard)
Liquid chromatography method for maleic anhydride in workshop air After the maleic anhydride in the air is collected with phosphoric acid solution, it is directly injected and separated by chromatographic separation. It is detected by ultraviolet-visible spectrophotometric detector (wavelength 254nm), and the retention time is used for qualitative analysis and the height is used for quantitative analysis. A2 Instruments
A2.1 Multi-hole glass plate absorption tube.
A2.2 Air sampler.
A2.3 Sample injector, data processing device or device with the same function. A2.4 High performance liquid chromatograph, ultraviolet-visible spectrophotometric detector. Chromatographic column: Column length 25 rm, inner diameter 4.6 II stainless steel column. Filler: YWG-C8+10μm.
Column temperature: 35C.
Column: 62 kgf/cm2c
Mobile phase: absorption liquid.
Flow rate, 1 ml/min.
A3 Reagents
A3.1 Absorption liquid: Take 0.1 ml. 85% (W/W) phosphoric acid and dilute to 1000 ml with banana distilled water. A3.2 Mamic acid (99.5%. Analytical purity)
A4 Sampling
Fill the absorption tube with 10 ml absorption liquid, connect the sampler, and collect 100 L of air at a flow rate of 1 L/min. A5 Analysis steps
A5.1 Control test: bring the absorption tube with absorption liquid to the site, except that no air sample is collected, operate with the same sample as the blank control. bZxz.net
A5.2 Drawing of standard curve: Accurately weigh 0.0050g maleic anhydride, dissolve it in a small amount of mobile phase, and dilute it to 50mL with mobile phase - the concentration of this solution is 100 μg/mL. Take 1 mL of this solution in a 15 mL volumetric flask, dilute it to the scale with mobile phase, and the concentration of the solution is 6.7ug/ml. Take 5μl of this solution. (0.033μg), 10μL (0.067μg), 20 (0.132) and repeat the injection 6 times respectively. Use the number of samples as the horizontal axis and the peak height of the sample as the vertical axis to draw the standard curve. A5.3 Determination of samples: Use the absorption liquid in the absorption tube to purge the air inlet tube 3 to 4 times, then blow the collected sample into the test tube, inject it, and the determination results are shown in Figure 1.
A6 Calculation
GB 18537-2001
Figure 1 Chromatogram of sample
A6.1 Convert the sampling volume into the volume under standard conditions according to formula (A1). V,= V, x
273 +t
Wu Zhong: V.-
Convert the sampling volume into the standard state, L; V is the sampling volume at tC. L;
The air temperature at the sampling point,;
The air pressure at the sampling point, kPa.
A6.2 Calculate the concentration of maleic anhydride in the air according to formula (A2).
-Liquidity of maleic anhydride in the air, mg/m3
-Find out the amount of maleic anhydride in the sample from the standard curve, name. V-
-Injection volume,.
-rKAoNrKAca-
（A1)
（A27
GB 18537—2001
V. Converted to the sampling volume under standard conditions, L. 10000-
A7 Explanation
Absorption liquid volume,,
A7.1 The detection limit of this method is 1.3×10-\g (injection of 10μL liquid sample). The minimum detection concentration is 0.01mg/m (collecting 100L air sample, the maleic anhydride content is 0.033μg, and the coefficients of variation at 0.0G7 and 0.132 are 3.4%, 1.5% and 0.8% respectively. The linear range is 0~0.13g.
A7.2 The sampling efficiency of this method is above 99.96%. The spike recovery rate is 96%~102%. A7.3 In order to ensure the sample When measuring under the same conditions as the standard, it is necessary to pay attention to the pH value of the mobile phase. When the pH value of the mobile phase is between 2.5 and 3.0, the measured value of the sample is within the control line. In addition, as the pH value of the mobile phase changes, the sample retention time also changes. Therefore, in order to reduce the error, the mobile phase, absorption liquid and standard push substance should be prepared using a phosphoric acid solution prepared at the same time. A7.4 The sample can be stored at room temperature (27C) for three days, and the fifth day will be reduced by 16.6% to 55.7%. Since maleic anhydride is volatile, the sample should be sealed and stored
A7.5 On-site samples of maleic anhydride production were found to interfere with the determination. For other production sites, appropriate chromatographic conditions can be selected according to the situation of the coexisting substances to eliminate interference.
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