This standard specifies the maximum permissible concentration and time-weighted average permissible concentration of oxalic acid in workshop air and its determination method. This standard is applicable to all types of enterprises that produce and use oxalic acid. GB 16245-1996 Hygienic standard for oxalic acid in workshop air GB16245-1996 Standard download decompression password: www.bzxz.net

GB16245-1996
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 health standard used for workplace environmental monitoring and health supervision. This standard shall be implemented from September 1, 1996. Appendix A of this standard is the appendix to the standard.
This standard is proposed by the Ministry of Health of the People's Republic of China. The drafting unit of this standard: Harbin Medical University. The main drafters of this standard: Luo Shengqing, Ma Baojun, Zhang Yifan. This standard is interpreted by the Institute of Labor Hygiene and Occupational Diseases of the Chinese Academy of Preventive Medicine, which is the technical management unit entrusted by the Ministry of Health. 574
National Standard of the People's Republic of China
Health standard for oxalic acid in the air of workplace
GB162451996
This standard specifies the maximum allowable concentration and time-weighted average allowable concentration of oxalic acid in the air of workplace and its determination method. This standard applies to all types of enterprises that produce and use oxalic acid. 2 Hygiene requirements
The maximum allowable concentration of oxalic acid in workshop air is 2 mg/m. The time-weighted average allowable concentration of oxalic acid in workshop air is 1 mg/m2. 3 Monitoring and inspection methods
For the determination method of oxalic acid concentration in workshop air, see Appendix A (Appendix to the standard). Approved by the State Bureau of Technical Supervision on April 3, 1996, and implemented on September 1, 1996bzxZ.net
A1 Principle
GB 16245-1996
Appendix A
(Appendix to the standard)
Ion chromatography of oxalic acid
Use filter membrane or absorption tube to collect oxalic acid dust or vapor respectively, elute the filter membrane with deionized water, separate it through ion chromatography column, and detect it with conductivity detector. The retention time is used for qualitative analysis and the peak height is used for quantitative analysis. A2 Instruments
A2.1 Sampling clip, filter membrane effective diameter 35mm, for large flow sampling. A2.2 Small sampling clip, filter material effective diameter 20mm, for small flow sampling. A2.3 Porous glass plate absorption tube.
A2.4 Filter material: perchlorethylene fiber filter membrane (dust filter membrane), the diameter depends on the sampling clip used. A2.5 Dust sampler, 0~25L/min, for large flow sampling. A2.6
Gas sampler, 0~3L/min, for small flow sampling and absorption tube sampling. A2.7 Stoppered test tube, 25mL.
A2.8 Micro syringe: 50μL.
A2.9 Ion chromatograph
Chromatographic column: IC-A1, 4.6mm×10cm, stainless steel. Column temperature: 40℃.
Detection chamber temperature: 40℃.
Eluent flow rate: 1.0mL/min.
A3 Reagents
A3.1 Deionized water: water with a resistivity greater than 2MQ obtained by passing distilled water through an ion exchange resin column. A3.2 Oxalic acid, analytical grade.
A3.3 Eluent: accurately weigh 0.415g of phthalic acid, dissolve in about 900mL of deionized water, adjust pH to 3.45 with tri(hydroxy)methylamine, and then dilute to 1000mL with deionized water. The concentration of this solution is 2.5mol/l. Before use, filter with a microporous filter membrane with a pore size of 0.45μm. A3.4 Standard solution: accurately weigh 1.0000g of oxalic acid, dissolve in deionized water, quantitatively transfer to a 1L volumetric flask, and dilute to the scale. 1mL of this solution = 1000μg oxalic acid. Before use, dilute with deionized water to a standard solution of 1mL=10μg, and filter with a microporous filter membrane with a pore size of 0.45μm.
A4 Sampling
A4.1 When oxalic acid exists in the form of vapor, connect two porous glass plate absorption tubes in series, each filled with 5mL of deionized water, and extract 5L of air sample at a speed of 0.5L/min.
A4.2 When oxalic acid exists in the form of dust, use a sampling clamp (A2.1) for large flow sampling, install a dust filter membrane with a diameter of 40mm, and extract 200L of air sample at a speed of 20L/min.
A4.3 When oxalic acid exists in the form of dust, use a small sampling clip (A2.2) for low-flow sampling, install a dust filter with a diameter of 25mm, and extract air at a speed of 1 to 21. /min for more than 4 hours. A5 Analysis steps
A5.1 Control experiment: Bring the sampling clip with the filter or the absorption tube with the absorption liquid to the site, but do not extract air, operate with the same sample, and use 576
as a blank control.
GB162451996
A5.2 Sample treatment: Place the collected filter in a test tube, add 10mL of deionized water and shake for 5 minutes. Combine the absorption liquid in the two absorption tubes. After the eluate and the absorption liquid are filtered through a microporous filter with a pore size of 0.45um, they are used for determination. A5.3 Drawing of standard curve: Prepare standard tubes according to Table A1. Table A1
Standard solution, mL
Deionized water, ml
Oxalic acid content, g
Preparation of oxalic acid standard tube
Use a microsyringe to take 50μL of oxalic acid standard solution for injection, and measure according to the instrument operating conditions of A2.9. Repeat the measurement for 3 times for each concentration, take the average value of the peak height, and draw a standard curve with oxalic acid content (μg) versus peak height; retention time is a qualitative indicator. A5.4 Determination: Take 50μL of sample solution (A5.2) and blank control solution (A5.1), and measure under the same operating conditions as the standard tube, and use retention time for qualitative analysis. After subtracting the peak height of the blank control from the peak height of the sample, the oxalic acid content (μg) in the sample is obtained from the standard curve. A6 Calculation
A6.1 Convert the sample volume into the volume under standard conditions according to formula (A1). Where: V
V. V× 273+t>
The sample volume under standard conditions, L;
The volume of air collected when the temperature at the sampling location is t, L, pThe atmospheric pressure at the sampling location, kPa;
-The temperature at the sampling location, ℃.
A6.2 Calculate the oxalic acid concentration in the air according to formula (A2). x=
Where: X-oxalic acid concentration in the air, mg/m; C-oxalic acid content found on the standard curve, μg; V. —The sampling volume under standard conditions, L. A7 Explanation
(A1)
A7.1The detection limit of this method is 0.1 uμg/mL, and the linear range is 0.1～1000μg/mL. When the oxalic acid concentration is 0.2μg/mL and 0.8μg/mL, the relative standard deviation is 3.75% and 1.55% respectively. A7.2 The average recovery rate of the filter membrane elution of this method is 101%. A7.3 This method is not affected by organic acids, inorganic acids, oxidizing and reducing substances in the on-site air. A7.4 The collected oxalic acid samples (absorption liquid) are stored at 4°C.
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