This standard specifies the determination of pyridine concentration in the atmosphere of residential areas by cyanogen chloride-barbituric acid spectrophotometry. This standard applies to the determination of pyridine concentration in the atmosphere of residential areas. GB/T 11732-1989 Standard method for hygienic examination of pyridine in the atmosphere of residential areas Cyanogen chloride-barbituric acid spectrophotometry GB/T11732-1989 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Standard method for hygienic examination ofpyridine in air of residential areas-Cyanogenchloride-barbituric acid spectrophotometric method
Standard method for hygienic examination ofpyridine in air of residential areas-Cyanogenchloride-barbituric acid spectrophotometric method1 Subject content and scope of application
This standard specifies the determination of pyridine concentration in air of residential areas by cyanogenchloride-barbituric acid spectrophotometric method. This standard is applicable to the determination of pyridine concentration in air of residential areas. 1.1 Sensitivity
10mL absorption solution containing 1μg pyridine can produce an absorbance of 0.08±0.01. 1.2 Detection limit
GB 11732-89
The detection limit is 0.4μg/10mL pyridine. When the sampling volume is 20L, the minimum measurable concentration is 0.02mg/m2. 1.3 Measurement range
The measurement range is 0.4~15ug in 10mL absorption liquid. When the sampling volume is 20L, the measurable concentration range is 0.02~0.75mg/m2. 1.4 Interference and exclusion
This method determines total pyridine and its derivatives. Generally, ammonia, amines, alcohols and ketones have no interference with this method. 2 Reference Standards
GB11736 Standard Method for Sanitary Inspection of Chlorine in Air of Residential Areas Methyl Orange Spectrophotometry 3 Principle
After pyridine in the air is absorbed by dilute hydrochloric acid, it reacts with barbituric acid in the presence of fluorine to generate a red-purple compound of dibarbituric acid glutaraldehyde. The colorimetric quantification is performed according to the color depth. 4 Reagents and Materials
The experimental water is deionized water, and the purity of the reagents used is analytical grade unless otherwise specified. 4.1 Absorption solution: 0.01mol/L hydrochloric acid solution. 4.2 0.1mol/L hydrochloric acid solution: Measure 8.3mL concentrated hydrochloric acid and dilute to 1L with water. 4.3 2% potassium cyanide solution 1)
Note: 1) Potassium cyanide is an extremely toxic drug.
4.4 1% Fluoramine T solution: Prepare immediately before use.
4.5 Barbituric acid solution: Weigh 1.25g barbituric acid and dissolve it in 100mL 1+1 acetone aqueous solution. 4.6 Standard solution: Add about 10mL 0.01mol/L hydrochloric acid solution to a 25mL volumetric flask, weigh accurately, then add 2-3 drops of freshly distilled pyridine, weigh accurately again, the difference between the two weights is the weight of pyridine. Add 0.01mol/L hydrochloric acid solution to dilute to the scale, and calculate the number of milligrams of pyridine per milliliter of solution. When used, use 0.01mol/L hydrochloric acid to prepare 1.00mL of 1μg pyridine standard solution. Approved by the Ministry of Health of the People's Republic of China on September 21, 1989 and implemented on July 1, 1990
5 Instruments and equipment
GB 11732-89
5.1 Porous glass plate absorption tube: See 4.1 of GB11736.5.2 Empty sampler: Flow range 0.2~1L/min, stable flow. When in use, use a soap film flowmeter to calibrate the flow of the sampling series before and after sampling. The flow error should be less than 5%. 5.3 Stoppered colorimetric tube: 25mL, volume error less than 1%. 5.4 Spectrophotometer: Use a 20mm colorimetric dish to measure the absorbance at a wavelength of 580nm. 6 Sampling
Use a porous glass plate absorption tube with 10mL of absorption liquid, and sample 10~20L of gas at a flow rate of 0.5L/min. Record the temperature and atmospheric pressure at the sampling point.
7 Analysis steps
7.1 Drawing of standard curve
Take 7 25mL stoppered colorimetric tubes, add 2mL 0.1mol/L hydrochloric acid, 1mL 2% potassium cyanide and 5mL 1% chloramine T to each tube in turn, shake well, and immediately prepare standard colorimetric tubes according to Table 1. Table 1
Absorbent solution, mL
Standard solution, mL
Pyridine content, μg
Standard colorimetric tubes
After shaking well, add 2mL barbituric acid solution to each tube, add water to the scale, and shake well. Put it in a 40℃ water bath, take it out after 45 minutes and let it cool. Use 20mm colorimetric IIIl, use water as a reference, and measure the absorbance at a wavelength of 580nm. With pyridine content (μg) as the horizontal axis and absorbance as the vertical axis, draw a standard curve, calculate the slope of the regression line, and use the reciprocal of the slope as the calculation factor B (μg/absorbance) for sample determination. 7.2 Sample determination
After sampling, add 2mL 0.1mol/L hydrochloric acid, 1mL 2% potassium cyanide and 5mL 1% chloramine T in a 25mL colorimetric tube in turn. After shaking, transfer all the absorption liquid into the colorimetric tube, wash the absorption tube with a small amount of water, combine the washing liquid into the colorimetric tube, and then continue to measure the absorbance according to the steps of drawing the standard curve. At the same time, use a 10mL unsampled absorption tube as a blank determination of the reagent. If the concentration of the sample solution exceeds the upper limit concentration of the standard color column tube, the sample can be diluted before determination. When calculating the concentration, the dilution multiple of the sample solution should be taken into account.
Result calculation
8.1 Convert the sampling volume into the sampling volume under standard conditions according to formula (1); Vo=Vt
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Wherein:. —Converted into the sampling volume under standard conditions, L, V, —--Sampling volume, L,
-Absolute temperature under standard conditions, 273K, T.-
--Temperature of the sampling point during sampling, ℃, P. --Atmospheric pressure under standard conditions, 101.3kPa, p--Atmospheric pressure of the sampling point during sampling, kPa. 490
Calculate the pyridine concentration in the air according to formula (2): C
GB 11732-89
(A-Ao)×Bs
Wherein: c ---Pyridine concentration in the air, mg/m°, A——Absorbance of the sample,
A. ——Absorbance of reagent blank:
B, a calculation factor obtained from 6.1, microgram/absorbance, D—the dilution factor of the analyzed sample solution. 9 Precision and accuracy
(2)
The recovery rate of the sample with 4μg pyridine standard was 100-103%. The combined coefficient of variation of repeated determinations of pyridine sample solutions with a concentration range of 0.4-4.0μg/10mL was 3%. Additional notes:
This standard was proposed by the Health Supervision Department of the Ministry of Health. This standard was drafted by the Jiangsu Provincial Health and Epidemic Prevention Station and the Nanjing Municipal Health and Epidemic Prevention Station. The main drafters of this standard were Wu Caigang, Shi Xiaoping, Hu Wenying, and Huang Fuxin. This standard is interpreted by the Environmental Health Monitoring Institute of the Chinese Academy of Preventive Medicine, which is the technical management unit entrusted by the Ministry of Health. 491
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