This standard specifies the method for the determination of vanadium pentoxide concentration in workshop air by N-cinnamoyl-o-toluylhydroxylamine spectrophotometry. This standard is applicable to the determination of vanadium pentoxide concentration in workshop air where vanadium pentoxide is produced and used. GB/T 16105-1995 Method for the determination of vanadium pentoxide in workshop air by N-cinnamoyl-o-toluylhydroxylamine spectrophotometry GB/T16105-1995 Standard download decompression password: www.bzxz.net

GB/T161051995
This standard is a monitoring method for labor hygiene standards, used to monitor the concentration of vanadium pentoxide in workshop air. This standard refers to foreign monitoring methods and is proposed after laboratory research and field verification in combination with my country's situation. 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: Sichuan Provincial Health and Epidemic Prevention Station. The main drafters of this standard: Wu Bixu and Zhao Chengli. The Ministry of Health entrusted the technical unit, the Institute of Labor Hygiene and Occupational Diseases of the Chinese Academy of Preventive Medicine, to interpret this standard. 1 Scope
National Standard of the People's Republic of China
Workplace air-Determinatiun of wanadium. pcntoxidc- -N-cinnamoyl-o-tol yl-hydroxylamine spectrophotometrie methodGB/T 16105 1995
This standard specifies the method for determining the concentration of vanadium pentoxide in workshop air by N-cinnamoyl-o-tol yl-hydroxylamine spectrophotometry. This standard is applicable to the determination of vanadium pentoxide concentration in the air of workshops that produce and use vanadium pentoxide. 2 Principle
Vanadium and N-hydroxylamine produce a red complex in hydrochloric acid, which is extracted with chloroform and quantified by colorimetry 3 Instruments
3.1 Sampling,
3.2 Filter material: slow quantitative filter paper-perchlorethylene filter membrane, 3.3 Vacuum.
3. 4 Flowmeter, 0)~10 1/min, 0-~25 L/min. 3.5 Stoppered colorimetric tube, 10mL.
3.6 Spectrophotometry,
4 Reagents
The purity of the reagents used in this method should be analytical grade. The reference reagent is required to be of high grade. 4. 1 Sulfuric acid, p=1, 84 g/ml.
4.2 Phosphoric acid, Psu-1. 685 g/mLc
4. 3 Nitric acid, p2zm—1. 42 g/ml. 4.4 Perchloric acid, P2:=1. 67 g/rrL,
4.5 Potassium permanganate solution, 2.5 g/1.
4.6 Aminosulfonic acid solution, 0.5/L
4.7 Saturated sodium sulfate solution.
4. 8 Hydrochloric acid, 0.2—1. 18 g/ml.
4.9 N-cinnamoyl-o-toluenehydroxylamine chloroform solution, 2.5/L: Weigh 0.25g N-cinnamoyl-o-toluenehydroxylamine [C,H,CH=CH-CO-N(OH)C,H,CH3, referred to as N-CTHA: dissolve in 100ml chloroform. 4.10 Standard solution: Weigh 0.1000g 105 dried for 1h vanadium pentoxide, dissolve in 10mL 50g/L sodium hydroxide solution, transfer to 500ml, volumetric flask, add 5ml 1+1 sulfuric acid, add water to the scale, and mix with a spoon. This solution is 1mL-200μg vanadium pentoxide, which is the stock solution. Approved by the State Administration of Technical Supervision on December 15, 1995 and implemented on July 1, 1996
GB/T16105—1995
Measure 5.0ml of the purchased solution in a 100mL volumetric bottle, add water to the mark, and prepare a standard solution of 1mL=10μg vanadium pentoxide. 5 Sampling
Vanadium pentoxide smoke is collected with filter paper. Fix the filter paper on the sample clamp and extract 100L of air at a speed of 5L/min. Vanadium pentoxide dust is collected with a filter membrane. Fix the filter membrane on the clamp and extract 100L of air at a speed of 20L/min. 6 Analysis steps
6.1 Control test, bring the sample with the filter membrane to the sampling point, except that the air is not collected, the rest of the operation is the same as the sample, as the blank control of the sample.
6.2 Sample treatment Place filter paper or filter membrane in a 50mL conical flask, add 2.5ml sulfuric acid and 5mL nitric acid. If heated, digest until the solution is transparent. Otherwise, continue to add nitric acid, 1-2mL each time, until the solution is light yellow. Cool slightly, carefully add 5 drops of perchloric acid, continue to heat until white smoke appears, remove and cool. Add 2ml phosphoric acid and 5mL water, heat until bubbles escape and smoke appears. Cool slightly, transfer to a 10ml colorimetric tube, wash the conical flask with a small amount of water, add the washing liquid to the colorimetric tube and dilute to the scale with water, mix well. For determination, 6.3 Drawing of standard curve Take 6 separatory funnels and prepare standard tubes according to Table 1. Table 1 Preparation of vanadium pentoxide standard tube
Standard solution, ml.
Content of vanadium pentoxide, g
Add 1ml sulfuric acid and 1mL phosphoric acid to each standard tube, add potassium permanganate solution dropwise until it becomes a stable light red color, and let stand for 2min. Then add 2ml aminosulfonic acid solution and 2mL saturated sodium fluoride solution, then add 8ml hydrochloric acid (so that the final solution concentration is 4mol/L hydrochloric acid), dilute to 25mL with water, shake well, add 5ml V-carboxyl-o-toluylhydroxylamine chloroform solution, shake for 2min, let it stand for stratification, wipe off the water in the lower tube of the separatory funnel with a filter paper strip, put the chloroform layer into a colorimetric tube, and compare the color at a wavelength of 530nm. Plot the vanadium pentoxide content () against the absorbance to draw a standard curve. 6.4 Determination Take 5.0 mL of the treated sample solution into a separatory funnel, add 7 mL of water, and drop potassium permanganate solution until it turns a stable light red color. The following operations are the same as those of the standard tube. The colorimetric base is used to find the content of vanadium pentoxide (g) on ​​the standard curve. 7 Calculation
7.1 Convert the sample volume to the volume under standard conditions according to (1). Vx
Sample volume under standard conditions, 1;
Where. V.
VSample volume, I.;
tTemperature.℃
p—Atmospheric pressure, kPa.
7.2 Calculate the concentration of vanadium pentoxide according to formula (2). 273
273 +
GB/T 16105—1995
Where: c—the concentration of vanadium pentoxide in the air, mg/m\; m——the content of vanadium pentaamine in the sample solution·g: V—the volume of the sample under standard conditions, L. 8 ExplanationwwW.bzxz.Net
8.1 The detection limit of this method is 2g/10mL. When sampling 100 L, the determination range of this method is 0.04～1mg/m. When the content of vanadium pentoxide is 10.30.50g/10ml., the coefficient of variation is 5.0%, 0.7% and 0.6% respectively. 8.2 The digestion recovery rates of filter paper and filter membrane are 97.1% and 93.9% respectively. 8.3 After sampling, fold the sampled filter paper or filter membrane in half, wrap it with clean filter paper, put it in a plastic bag, and put it in a box for long-term storage.
8.4 When processing the sample, the temperature should not be too high after adding phosphoric acid, and the digestion should not be too long, otherwise it is easy to produce colloidal substances that affect the determination. 8.5 The concentration of hydrochloric acid has a great influence on the extraction of the complex. 4mol/L hydrochloric acid concentration is the appropriate acidity for extraction. 8.6 Titr has no interference with this method. Fe3+ has interference above 200ug, but the interference can be eliminated by adding 2ml. 100'g/l. sodium hexametaphosphate. Crli- will not interfere when it is 20g,
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