Some standard content:
National Standard of the People's Republic of China
Health standard for monomethyl-hydrazine in the air of workplace
Health standard for monomethyl-hydrazine in the air of workplace Subject content and scope of application
This standard specifies the maximum allowable concentration of monomethyl-hydrazine in the air of workplace and the monitoring and inspection methods. This standard is applicable to all types of enterprises that produce and use monomethyl hydrazine. 2 Hygiene requirements
The maximum allowable concentration of monomethyl in the air of workplace is 0.08mg/m (skin). 3 Monitoring and inspection methods
For the monitoring and inspection methods of this standard, see Appendix A (supplement) and Appendix B (supplement). GB 16222-1996 approved by the State Administration of Technical Supervision on April 3, 1996
Implementation on September 1, 1996
A1 Principle
GB16222-1996
Appendix A
P-dimethylaminobenzaldehyde colorimetric method
(Supplement)
Use a solid adsorbent coated with sulfuric acid to collect monomethylhydrazine in the air, and react with p-dimethylaminobenzaldehyde after desorption to generate a yellow azine compound for colorimetric quantification.
A2 Instruments
A2.1 Stoppered graduated test tube: 25 ml.
A2.2 Graduated pipette: 20 mL, 10 mL, 5 mL, 1 ml. A2.3 Spectrophotometer.
A2.4 Air sampler: 0~2L/min.
A2.5 Sampling tube, make according to the following procedure: weigh 10.0g 40~60 mesh 101 white carrier, put it into a beaker, add 100mL distilled water, quickly heat and boil for 3min, pour out the upper turbid liquid, wash with distilled water until the rinse liquid is clear and transparent. Filter the carrier with a Buchner funnel until dry, then transfer it to the surface blood, spread it evenly, dry it at 70±1℃ for 40~50min, and transfer it to a dryer to cool. Weigh 4.0g of the washed carrier, spread it evenly on the surface blood, use a pipette to take 11.0mL of sulfuric acid-ethanol solution, evenly drip it on the carrier, air dry it in a fume hood, move it into a constant temperature drying oven at 80±1℃, dry it for 40min (until the carrier is loose), transfer it to a dryer to cool to room temperature, and bottle it for later use.
Weigh 300 mg of sulfuric acid-coated support and put it into a glass tube (90 mm long, 6 mm inner diameter). Fix the two ends of the support with a clean 60-mesh stainless steel mesh. After installation, seal it with a polyethylene cap in time. A3 Reagents
A3.1 Sulfuric acid: high-grade pure.
A3.2 Anhydrous ethanol: high-grade pure.
A3.3 Ethanol: analytical grade.
A3.4-Methyl tantalum: propellant grade product with a purity of more than 98.5%. A3.5 p-Dimethylaminobenzaldehyde: analytical grade. A3.6101 White support: 40-60 mesh.
A3.7 Sulfuric acid solution: c(H,SO.) 0.15 mol/L. A3.8 Sulfuric acid solution: c(H,SO,) = 6 mol/L. A3.9 p-Dimethylaminobenzaldehyde solution: Weigh 15.0g p-dimethylaminobenzaldehyde and dissolve it in 500mL ethanol, add 4.2mL sulfuric acid (A3.1), and shake well. It can be stored at room temperature for two weeks. A3.10 Sulfuric acid-ethanol solution: Add 36mL sulfuric acid solution (A3.8) to 200mL anhydrous ethanol, and then dilute to 250mL with anhydrous ethanol. A3.11 Standard solution: Add about 70mL sulfuric acid solution (A3.7) to a 100mL volumetric flask, cover with a stopper, and accurately weigh about 0.115mL monomethylhydrazine (weighed to 0.1mg) on an analytical balance using a syringe by the reduction method. When weighing, seal the needle tip with a small piece of rubber. Carefully inject monomethylhydrazine into the volumetric flask, shake gently, and dilute to the scale with sulfuric acid solution (A3.7) after 20 minutes. Shake well to obtain a 1.0mg/mL standard stock solution, which can be stored at low temperature for half a year.
Take another 100mL volumetric flask, add about 70mL sulfuric acid solution (A3.7), 1mL standard stock solution, and then dilute to the mark with sulfuric acid solution (A3.7). This is the standard solution, and the methyl argon content is about 10 μg/mL. 509
A4 Sampling
GB 16222--1996
Remove the polyethylene caps at both ends of the glass sampling tube at the sampling site, connect the - end to the air sampler, place the sampling tube vertically with the tube mouth downward, and collect 30~~50L of air at a rate of 1I/min. After sampling, seal both ends of the sampling tube with polyethylene caps, put it in a plastic bag, and send it to the laboratory for analysis. A5 Analysis steps
A5.1 Control test: Bring the sampling tube to the sampling site, remove the polyethylene caps at both ends but do not collect air, and then seal it with a polyethylene cap and keep it for a control test.
A5.2 Sample treatment: Transfer the supports of the sample and control test sampling tubes into graduated test tubes respectively, rinse the sampling tube wall 3 to 4 times with a small amount of sulfuric acid solution (A3.7), leave for 5 minutes, add 10mL of p-dimethylaminobenzaldehyde solution, dilute to the scale with sulfuric acid solution (A3.7), invert 5 times to mix, and color develop at room temperature for 30 minutes. A5.3 Drawing of standard curve: Take 7 stoppered graduated test tubes, add 300 mg of sulfuric acid-coated support to each, two of which are used as blanks, and add 0.2, 0.4, 0.6, 0.8, and 1.0 mL of 10 μg/mL monomethylhydrazine standard solution to the remaining 5 tubes, respectively. Then add 10 mL of p-dimethylaminobenzaldehyde solution to each tube, dilute to scale with sulfuric acid solution (A3.7), invert 5 times to mix, and color develop at room temperature for 30 minutes. Then use 2 cm colorimetric blood, wavelength 470 nm, and adjust to zero with distilled water. Measure the absorbance of the upper clear liquid of each tube, and subtract the average absorbance of the blank to obtain the net absorbance of each solution. Draw the -methylhydrazine content (μg)-absorbance curve. A5.4 Determination: Determine the absorbance of the sample according to the conditions and steps for making the standard curve, and find the monomethylhydrazine content (μg) from the standard curve after subtracting the average absorbance of the control test tube. A6 Calculation
Where: X—concentration of monomethylhydrazine in air, mg/m3; C——measured monomethylhydrazine content, μg;
V. ——sample volume under standard conditions, L. A7 Explanation
·(Al)
A7.1 The minimum detection concentration of this method is 0.0031mg/m3 (sampling volume 100L). The determination range is 0.0102.5mg/m3. The average coefficient of variation within this range is 3.6%.
A7.2 Ammonia, nitrogen dioxide, sulfur dioxide, and unsymmetrical dimethylhydrazine in the air do not interfere with the determination of monomethylhydrazine. The oxidation product of unsymmetrical dimethylhydrazine shows positive interference, and unsymmetrical dimethylhydrazine seriously interferes with the determination of monomethylhydrazine. A7.3 The ambient temperature has an effect on the color development and color stability time. The sample absorbance decreases with the increase of ambient temperature. Therefore, the standard curve should be calibrated while the sample is being determined, and the color development time should be controlled according to the room temperature of the day, see Table A1. Table A1
Temperature.℃
Color development time, min
30～60
20～60
B1 Principle
GB 16222—1996
Appendix B
Gas chromatography
(Supplement)
Use a solid adsorbent coated with sulfuric acid to collect monomethylhydrazine in the air, desorb with sodium hydroxide solution, derivatize with 2,4-pentanedione, extract with ethyl acetate, separate with an OV-17/Supelcoport column, and detect with a hydrogen flame ionization detector. The qualitative analysis is based on the retention time and the quantitative analysis is based on the peak height. B2 Instruments
B2.1 Air sampler and sampling tube: Same as Appendix A (Supplement). However, a 6201 carrier is used instead of a 101 white carrier, and 200 mg of the treated carrier is placed in the tube.
B2.2 Test tube with stopper: 5mL.
B2.3 Microsyringe: 10μL, 50μL. B2.4 Gas chromatograph: oxygen flame ionization detector. Chromatographic column: 3m long, 4mm inner diameter, stainless steel column; 15% OV-17/Supelcoport 80-100 mesh filling; column temperature: 124℃-134℃,
Vaporization chamber temperature: 264℃;
Detection chamber temperature: 264℃,
Carrier gas: high-purity nitrogen, 70 mL/min.
B3 Reagents
2,4-Pentanedione: analytical grade.
Ethyl acetate: analytical grade.
Sodium hydroxide: analytical grade.
6201 carrier: 40-60 mesh.
Supelcoport support, 80-100 mesh. B3.6OV-17: Chromatographic stationary liquid.
B3.7 Sulfuric acid, anhydrous ethanol, methyl hydrazine, 6 mol/L sulfuric acid solution, sulfuric acid-ethanol solution, same as Appendix A (supplement). B3.8 Tung: Propellant grade product with purity above 98.5%. B3. 9 Sulfuric acid solution: c(H,SO,)=0.4 mol/L. B3.10 Sodium hydroxide solution: weigh 6.7329g of sodium hydroxide into a volumetric flask containing 300mL of distilled water, cool to room temperature and dilute to 500mL with distilled water.
B4 Sampling
The sampling operation steps and requirements are the same as those in Appendix A (Supplement). B5 Analysis steps
B5.1 Control test: The same as Appendix A (Supplement). B5.2 Sample treatment: Transfer the support of the sampled and control test sampling tubes into a stoppered graduated test tube, add 2mL of sodium hydroxide solution for desorption, then add 200μg of hydrazine and 2μL of 2,4-pentanedione, adjust pH to 9.0, react at room temperature for 60min, and extract with 0.5mL of ethyl acetate for 30502
min. bzxZ.net
GB16222—1996
B5.3 Drawing of standard curve: Prepare standard solution as in A3.11 of Appendix A (Supplement), add 200mg treated 6201 support, 2mL sodium hydroxide solution, 200μg tung respectively into 5 stoppered graduated test tubes, then add 5, 10, 15, 20, 25μL monomethyl hydrazine standard solution in sequence, then add 2μuL 2,4-pentanedione, shake and adjust pH=9, react at room temperature for 60min, extract with 0.5mL ethyl acetate for 30min, take 10μL extract for injection, repeat 3 times for each concentration. Qualitative analysis is performed by retention time, and the average peak height is plotted against the monomethyl hydrazine content to draw the standard curve.
Monomethylhydrazine chromatogram
B5.4 Determination: According to the conditions for drawing the standard curve, take 10μL of sample extract and inject it, repeat 3 times, subtract the peak height of the control test from the average peak height, and obtain the monomethylhydrazine content (μg) from the standard curve. B6 Calculation
Where: X--monomethylhydrazine concentration in the air, mg/m, C-measured monomethylhydrazine content μg,
V. Sample volume under standard conditions, L. x=.
B7 Explanation
GB16222-1996
B7.1 The minimum detection concentration of this method is 0.0042mg/m (sampling volume 100L), the determination range is 0.01mg/m2~2.5mg/m2, and the average coefficient of variation of the method is 2.6%. B7.2 Adding 200 μg hydrazine or 140 ug UDMH can eliminate the interference of hydrazine and UDMH and improve the sensitivity of the method. Additional Notes:
This standard is proposed by the Ministry of Health of the People's Republic of China. This standard was drafted by the Seventh Design Institute of the Ministry of Aerospace Industry, and participated in by the Institute of Toxicology and Pharmacology of the Academy of Military Medical Sciences and the 101st Institute of the Ministry of Aerospace Industry.
The main drafters of this standard are Wang Xinchao, Xia Yadong and Zhu Mingsheng. This standard is interpreted by the Institute of Labor Hygiene and Occupational Diseases of the Chinese Academy of Preventive Medicine, the technical unit entrusted by the Ministry of Health. 50.1
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