Some standard content:
National Standard of the People's Republic of China
Health standard for selenium in the air of workplace
Health standard for selenium in the air of workplace Subject content and scope of application
This standard specifies the maximum allowable concentration of selenium in the air of workplace and its monitoring and inspection methods. This standard is applicable to all types of enterprises that produce and use selenium. Hygiene requirements
The maximum allowable concentration of selenium in the air of workplace is 0.1mg/m. Monitoring and inspection methods
The monitoring and inspection methods of this standard adopt fluorescence determination method, see Appendix A (supplement). GB162171996 approved by the State Administration of Technical Supervision on April 3, 1996
Implementation on September 1, 1996
A1 Principle
GB 16217--- 1996
Appendix AbzxZ.net
Fluorescence determination method
(Supplement)
Selenium in the air is collected on a microporous filter membrane. After the filter membrane sample is digested with nitric acid-perchloric acid, selenium reacts with 2,3-diaminonaphthalene under acidic conditions to generate a light orange fluorescent compound, which is extracted with cyclohexane and the selenium content is determined based on the fluorescence intensity. A2 Instrument
A2.1 Sampling clip.
A2.2 Filter material: microporous filter membrane, pore size 0.8um, diameter 40mm. A2.3 Vacuum.
A2.4 Flowmeter, 0~10L/min.
A2.5 Conical flask or tall beaker, 50ml. A2.6 Small funnel, 40mm diameter.
A2.7 Electric hot plate.
A2.8 Stoppered colorimetric tube, 50mL.
A2.9 Fluorescence spectrophotometer or fluorescence photometer, 10mm colorimetric cup. Excitation light wavelength, 378nm, slit 10nm; emission light wavelength, 520nm, slit 4nm. A3 Reagents
A3.1 Deionized water or double distilled water.
A3.2 Nitric acid, P2o=1.42g/mL, high-grade purity. A3.3 Perchloric acid, P2o=1.67g/mL, high-grade purity. A3.4 Hydrochloric acid, P2o=1.18g/ml, high-grade purity. A3.5 Perchloric acid-nitric acid, 1+9.
A3.6 Hydrochloric acid solution, 1+1.
A3.7 Cyclohexane, high purity.
A3.8 2,3-Diaminonaphthalene (DAN) solution, 0.1g/L, this solution needs to be prepared in a dark room. Weigh 100mg of analytically pure diaminonaphthalene into a conical flask with a ground stopper, add 100mL 0.1mol/L hydrochloric acid, shake for 15min until completely dissolved, add about 20mL cyclohexane, shake for 5min, transfer to a separatory funnel, after stratification, extract the lower layer solution with cyclohexane for 3 to 4 times. Until the fluorescent impurities in cyclohexane are reduced to the minimum. Finally, collect the lower layer solution in a brown bottle and store it for one year. A3.9 Disodium ethylenediaminetetraacetic acid (EDTA) solution, 74g/L. A3.10 Hydroxylamine hydrochloride solution, 10g/L.
A3.11 Cresol red ethanol solution, 0.02g/L. Weigh 20mg of cresol red, add 1mL of 0.05mol/L sodium hydroxide solution, 2mL of ethanol, heat and dissolve, dilute to 100mL with 20% ethanol. A3.12 Ammonium hydroxide solution, 1+1.
A3.13 Selenium standard solution, weigh 0.1634g of selenious acid and dissolve in 1L of water, 1mL of this solution = 0.1mg of selenium. Dilute with water before use to 1ml, 1. 0μg of selenium standard solution.
A4 Sampling
GB 16217--1996
Install the microporous filter in the sampling clip and collect 75L of air sample at a speed of 5L/min. A5 Analysis steps
A5.1 Control test: Take the unsampled microporous filter membrane (A2.2) to the site, but do not extract air. Perform the same sample treatment as the blank control.
A5.2 Sample treatment: Place the sampled microporous filter membrane in a 50mL conical flask, add 5mL perchloric acid-nitric acid (A3.5), put a small funnel on it, place it on the hot plate, heat and digest, and control the temperature below 130℃ until white perchloric acid smoke appears. Cool it slightly, wash the inner wall of the conical flask and the small funnel with 10mL water, and then place it on the hot plate. Heat for 5min, remove it and cool it, transfer it quantitatively into a stoppered colorimetric tube, and dilute it with water to 20mL for determination.
A5.3 Drawing of standard curve: Take 6 stoppered colorimetric tubes (A2.8) and prepare standard tubes according to Table A1. Table A1 Preparation of Selenium Standard Tubes
Standard solution, ml.
Water, nl.
Selenium content,
Add 1 mL of disodium EDTA solution, 1 mL of hydroxylamine hydrochloride solution, and 2 drops of cresol red solution (A3.11) to each standard tube in turn. Use ammonia and hydrochloric acid (A3.6) to adjust the pH to 1.5~~2.0, so that the solution turns light orange. Add 1.5 mL of DAN solution in a dark room, mix well, boil in a boiling water bath for 5 minutes, take out, and cool with water. Add 5 ml of cyclohexane, oscillate on a vortex mixer for 2 minutes, take out the cyclohexane layer, and measure its fluorescence intensity. Draw a standard curve with selenium content and corresponding fluorescence intensity. A5.4 Sample determination: Take 1 mL of the sample treated in A5.2 into a stoppered colorimetric tube and add 19 mL of water. The following determination is carried out according to the operating conditions of A5.3, and the selenium content in the sample is obtained from the standard curve. A6 Calculate
X -20C/V.
Where: X—
Selenium concentration in air, mg/m;
—Selenium content in sample, ug;
V. ———Convert to sample volume under standard catalytic conditions, L. A7 Explanation
(Al)
A7.1 The detection limit of this method is 0.1μg/5mL, and the measurement range is 0.1~1μg/5mL. When the concentration is 0.3, 0.5, and 0.7μg/5mL, the coefficient of variation is 2.22%, 2.40%, and 3.11%, respectively. A7.2 The sampling efficiency of this method is 97.9%. During the sampling process, pollution should be prevented. Filter membranes should not be installed in places where high concentrations of selenium are produced. Sampling clamps and tweezers and other utensils should be kept clean. During sampling and transportation after sampling, dust on the filter membrane should be prevented from falling off. A7.3 After sampling, fold the filter membrane inward twice, wrap it with clean filter paper, put it in a small plastic bag and store it in a box. A7.4 Under the conditions of this method, 100μg of Cu2+, Hg2+, As3+, Pb3+, and Fe3+ have no interference with the determination. A7.5 Strictly control the digestion temperature and time of the sample. 481
Additional notes:
16217-1996
This standard was proposed by the Ministry of Health of the People's Republic of China. This standard was drafted by the Shanghai Municipal Health and Epidemic Prevention Station. The main drafters of this standard are Gu Qiuping and Li Yufen. This standard is interpreted by the Institute of Labor Hygiene and Occupational Diseases, Chinese Academy of Preventive Medicine, the technical management unit entrusted by the Ministry of Health. 482
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