GB 18540-2001 Occupational exposure limits for calcium oxide in workplace air
Some standard content:
GB18540—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 unit of this standard: Institute of Hygiene, Zhejiang Academy of Medical Sciences. The drafters of this standard are Hong Changfu, Ding Xiaobei, He Lingyuan, and Lou Jinping. This standard is entrusted to the Institute of Labor Hygiene and Occupational Diseases, Chinese Academy of Preventive Medicine for interpretation. 661
1 Scope
National Standard of the People's Republic of China
Occupational exposure limit for calcium oxide in the air of workplace
GB 18540—2001
This standard specifies the maximum permissible concentration of calcium oxide in the air of workplace, the time-weighted average permissible concentration and its monitoring and inspection methods. This standard is applicable to all types of industrial enterprises that produce and use calcium oxide. 2 Hygiene requirements
The maximum permissible concentration of calcium oxide in the air of workplace is 5mg/m3, and the time-weighted average permissible concentration is 2mg/m3. 3 Monitoring and inspection methods
The monitoring and inspection methods of this standard adopt flame atomic absorption spectrometry, 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, 2001662
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Implementation on May 1, 2002
A1 Principle
GB18540—2001
Appendix A
(Appendix to the standard)
Calcium oxide in workshop air Flame atomic absorption spectrometry Calcium oxide in air is collected on a microporous filter membrane, and the sample is digested with nitric acid and perchloric acid and dissolved in hydrochloric acid. The calcium oxide content is determined by acetylene-air flame atomic absorption spectrometry at a wavelength of 422.7nm. A2 Instrument
A2.1 Small plastic sampling clip
A2.2 Filter material: microporous filter membrane, pore size 0. 8 μmA2. 3 Air sampler: flow rate 0~10 T./min. A2.4 High beaker or conical flask: 50 ml. A2.5 Surface III: diameter about 5 cm.
A2.6 Electric heating plate or electric sand bath.
Stoppered colorimetric tube: 10 mL,
Atomic absorption spectrophotometer, equipped with acetylene-air flame burner, calcium hollow cathode lamp. A3 Reagents
The experimental water is deionized water,
43.1 Deionized water: water with a specific resistance greater than 500 k2·cm obtained by passing through an ion exchange resin column, or water obtained by re-distilling with a full glass evaporator.
A3.2 Nitric acid: p2a—1.42 g/ml, high-grade purity. A3.3 Perfluoric acid: Pzc=1.67g/mL, high grade pure. A3.4 Digestion solution: Mix nitric acid and perfluoric acid in 91. A3.5 Hydrochloric acid: =1.18g/ml.. high grade pure. A3.6 Hydrochloric acid solution: 1+9.
A3.7 Lanthanum solution (10mg/mL): Weigh 1.5g cesium nitrate (CsNC) or 1.27g calcium chloride (CsCt) and quench with water, dilute to 100 ml..
A3.8 Lanthanum solution (10 mg/ml.) Weigh 3.1g nitric acid [1.a(N(),): ~6H()] and quench with water, dilute to 100 mL. A3.9 Calcium standard solution: Dissolve 2.4980 g of calcium carbonate (superior purity) in 7) m. (2+5) hydrochloric acid aqueous solution: dilute with water to 11. This solution contains 1.0 mg calcium per ml. Dilute with water before use to a standard solution containing 50 μg calcium per ml. A4 Sampling
Install the microporous filter membrane in the sampling clip and collect air samples at a flow rate of 1.5L/min. After sampling, use clean tweezers to take the filter membrane out of the sampling clip, fold it inward twice, put it in a small plastic bag, and put it in a box for long-term storage. A5 Analysis Steps
A5.1 Control Test: Bring the sampling clip containing the microporous filter membrane that has not been sampled to the site. Except for not sampling, it is treated in the same way as the sample treatment operation as a blank control.
A5.2 Sample Treatment: Put the sampled microporous filter membrane into a tall beaker, add 5ml of digestion solution, cover the surface with 1ml of solution, and place it on an electric hot plate and add 1663
GB18540—2001
heat digestion until thick perchloric acid smoke appears. Cool, wash the surface III and the inner wall of the beaker with 5ml water, continue heating until dry, dissolve the residue with 5ml hydrochloric acid solution, transfer quantitatively into the colorimetric tube, wash the beaker with 3mL water, and put the washing liquid into the colorimetric tube. Then add 1mL cyanate solution and 1ml lanthanum solution, add water to 10ml, mix well: for determination. A5.3 Drawing of standard curve, take 6 stoppered colorimetric tubes, add 5mL hydrochloric acid solution, 1mL cyanate solution and 1mL solution to each, and prepare according to Table A1.
Preparation of calcium standard series
, name
Standard solution, mL
Calcium concentration, \g/mL
Adjust the flame absorption spectrophotometer to the optimal operating conditions, and measure the standard tubes respectively at a wavelength of 422.?nm using acetylene-air flame (high fuel gas flame). The measured absorbance value minus the absorbance value of the heart tube is used as the ordinate, and the calcium concentration is used as the abscissa to draw a standard curve.
A5. 4 Determination: Use the same instrument operating conditions as A5. 3 to measure the treated samples. For every 10 samples measured, calibrate the measurement results with a standard solution of medium concentration. After subtracting the absorbance value of the blank control from the absorbance value of the sample, the calcium concentration is obtained from the standard curve. wwW.bzxz.Net
A6 Calculation
A6.1 Convert the sample volume into the volume under standard conditions according to formula (A1). V,=V,×
273 +t
Where: V.——Sampling volume under standard conditions, L; —Temperature of sampling location,
—Atmospheric pressure at sampling location, kPa [If expressed in mmHg, 101.3 in formula (A1) is changed to 760]; —Sampling volume at t C and p, Ia
A6.2 Calculate the expansion of calcium oxide in the air according to formula (A2). 10×1.40
Where C.…Concentration of calcium oxide in the air, mg/m\, c—--Concentration of calcium in the sample found on the standard curve·μg/mL, V——Volume of the sample under standard conditions, L; 1.40-Coefficient for converting calcium into calcium oxide. A7 Description
(A2)
A7.1 The detection limit of calcium oxide in this method is 0.038g/mL, the sensitivity is 0.1g/mL (1% absorption), the minimum detection concentration is 0.56mg/m3 (sampling 251 air), and the measurement range is 1.0~10.0μg/mL. When the calcium concentration is 3, 5, and 7/ml, the coefficient of variation is 1.5%, 0.9%, and 1.1%, respectively.
A7.2 When the concentration of calcium oxide in the workshop air is 10.8~122.6mg/m3, the sampling efficiency is 99.8%~100%. Prevent sample contamination during sampling. Prevent dust from falling off the filter membrane during sampling, transportation, and storage. A7. 3 All glassware used for determination must be soaked in 1+1 nitric acid to prevent calcium contamination. A7.4 Under the conditions of this method, 5μg/mL Caa+1000μg/mL Na-, K*, 125μg/ml.1.i+, 100μg/mL PO-, 50μg/mL Al, SiOx+, 25μg/ml.Mg?+ have no interference with the determination.
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