GB/T 16108-1995 Spectrophotometric determination of zirconium and its compounds in workplace air using xylenol orange
Some standard content:
GB/T16108—1995
This standard is a monitoring method for labor hygiene standards, used to monitor the concentration of zirconium and its compounds in the air of workshops. This standard is proposed after laboratory research and field verification based on foreign monitoring methods and combined with the situation in my country. This standard will be implemented from July 1, 1996. This standard is proposed by the Ministry of Health of the People's Republic of China. The drafting unit of this standard is Shandong Provincial Institute of Labor Hygiene and Occupational Disease Prevention and Control. The main drafters of this standard are Fan Huamin and Qiu Baorong. The Institute of Labor Hygiene and Occupational Diseases of the Chinese Academy of Preventive Medicine, the technical unit entrusted by the Ministry of Health, is responsible for the interpretation of this standard. 1 Scope
National Standard of the People's Republic of China
Workplace air-Determination of zirconium and its compounds Xylenol orange spectrophotometric method GB/T 16108—1995
This standard specifies the method for determining the concentration of zirconium and its compounds in workshop air by xylenol orange spectrophotometric method. This standard is applicable to the determination of the concentration of zirconium and its compounds in the air of workshops where zirconium and its compounds are produced and used. 2 Principle
Zirconium and its compounds are collected on perchloroethylene filter membranes. The filter membrane samples are dissolved in hydrochloric acid. In a 0.5n1al/I. hydrochloric acid solution, zirconium ions react with monocresol orange to form a red complex, which is quantitatively measured by colorimetry. 3 Apparatus
3.1 Sampling cooler.
3.2 Filter material, perchloroethylene filter membrane.
3.3 Vacuum.
3.4 Flow meter, 0~10 L/min.
3.5 Stoppered colorimetric tube, 25mL.
3.6 Spectrophotometer, 10mm colorimetric cup.
4 Reagents
4. 1 2 mol/1. hydrochloric acid.
4. 2 0. 5 mol/L hydrochloric acid.
4.3 Xylenol orange solution, 0.4g/L. www.bzxz.net
4.4 Zirconium standard solution, weigh 0.3533g zirconium oxychloride (ZrOCl, ·8H,0), dissolve it with 2mol/1. hydrochloric acid, and then transfer it to a 100ml volumetric flask. Dilute to the mark with 2mol/l. hydrochloric acid, mix well, this solution 1mL = 1mg zirconium, when using, draw 1mL into a 100rmL volumetric flask, add 3mL distilled water, and then dilute to the mark with 0.5mol/L hydrochloric acid to make 1ml, = 10g zirconium standard solution, 5 Sampling
Fix the filter material in the sampling and mixing clamp and draw 10~15L of air at a speed of 5L/min. 6 Analysis steps
6.1 Control test
Bring the sampling clamp with the filter membrane to the sampling point, except not collecting air, the rest of the operation is the same as the sample, as the blank control of the sample. Approved by the State Administration of Technical Supervision on December 15, 1995, and implemented on July 1, 1996
GB/T 16108—1995
6.2 Sample treatment
6.2.1 For water-soluble zirconium compound samples, place the sampled filter membrane in a 25ml beaker, add 10mL 0.5mal/l hydrochloric acid, heat on a convex stove until it is almost boiling, remove and cool, transfer to a 25ml colorimetric tube, wash the beaker and filter membrane three times with 0.5mol/l hydrochloric acid, add the washing solution to the colorimetric tube, and dilute to the scale with 0.5mol/L hydrochloric acid and mix well. Take 10mL of the sample solution and place it in a colorimetric tube for determination. 6.2.2 For water-insoluble zirconium compound samples, such as zirconium dioxide (ZrO2), place the sampled filter membrane in a porcelain block, overlap two hollow refractory bricks on an electric furnace, place the crucible inside, cover it with a refractory sheet, heat it to asheen into a white residue, cool it, add 1 ml of ammonium sulfate-sulfuric acid solution (10 g of ammonium sulfate dissolved in 30 ml of concentrated sulfuric acid), heat it on an electric furnace to dissolve, and continue heating to remove sulfuric acid until it is evaporated to dryness. Then wash the crucible three times with an appropriate amount of 0.5 mol/l hydrochloric acid, add the washed solution into a 25 tml colorimetric tube, dilute to the scale, and mix well. The following steps are the same as 6.2.1.
If the sample is sodium zirconate (Na7.r), place the filter membrane in a 25,mL beaker, add 10mL 6 mol/1. acid, heat and stir on an electric stove until boiling. There is about 2ml left (do not evaporate to dryness), remove and cool, rinse the beaker 3 times with an appropriate amount of 0.5mol/L hydrochloric acid, add the rinsed solution into a 25ml colorimetric tube, and dilute to the scale, mix. The following steps are to 6.2.1. 6.3 Drawing of standard curve
Prepare standard tubes according to Table 1.
Table 1, preparation of standard tubes
Zirconium standard solution + mL
C. 5 mol/L hydrochloric acid, ml.
Zirconium content,
Add 1mL of diphenol orange solution to each standard tube and mix evenly. After 15 minutes, colorimetric at a wavelength of 540nm and draw a standard curve.
6.4 Sample determination
The sample determination is carried out under the same operating conditions as in 6.3. After colorimetry, the zirconium content is found from the standard curve. 7 Calculation
7.1 Calculate the sample volume under standard conditions according to formula (1). V. -- V× 273 +t
, where?V
The sample volume under standard conditions, .;
V--sampling volume. L,
The air temperature at the sampling site, C;
The atmospheric pressure at the sampling site, J. kPa.
7.2 Calculate the zirconium concentration in the air according to formula (2). 2.5m
Where, '
The concentration in the air, mg/m;
mThe content of the sample solution taken, g: V. --The sample volume under standard conditions,.力
8 Explanation
GB/T16108
8.1 The detection limit of this method is 0.7/10 ml., the linear range is 1~~20/10 mL, and the coefficient of variation is 5.3, 1.8%, 3.1, 0.9%, 0.5%, 0.8%, respectively.
8.2 Sampling efficiency, zirconium dioxide is 97.9%, zirconium oxynitride is 99.0%, and sodium metazirconate is 95%. 8.3 The recovery rate of this method, add zirconium oxychloride 1.5~4.8mg, sodium zirconate 1.2~3.5mg and zirconium dioxide 0.8~5.9mg on the filter membrane, the recovery rates are 104%, 103.6, and 97.9% respectively; the recovery rate of adding 10-~50% zirconium is 97.6%. 8.4 10 times the amount of iron as zirconium, 50 times the amount of argon, 15 times the amount of titanium, 60 times the amount of strontium, 80 times the amount of lead, 100 times the amount of calcium and magnesium will not interfere with the determination of zirconium; because the ratio of zirconium and arsenic coexisting is about 1/2, the interference of hafnium can be ignored when the concentration is low. 8.5 This method is easy to operate and has strong anti-interference ability. The absorbance remains constant from 15 minutes to 2 hours after color development. The xylenol orange solution can still be used after being stored in the refrigerator for 4 months.
8.6 When treating zirconium dioxide samples to remove sulfuric acid and sodium metazirconate to remove hydrochloric acid, care must be taken to observe and do not evaporate to dryness. Otherwise, it will affect the determination results.
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