GB/T 8912-1988 Standard method for the determination of arsenic compounds in the atmosphere of residential areas - Silver diethylaminodithiocarbamate spectrophotometric method
Some standard content:
National Standard of the People's Republic of China
Hygienic determination method of arsenide in air of residential areas-Silver diethyldithiocar-bamate spectrophotometric method1Scope of application
This standard is applicable to the determination of mass concentration of arsenide in the air of residential areas. 1.1Sensitivity
When the colorimetric volume is 5ml, 1μg should have an absorbance of 0.03. 1.2Lower limit of detection
The lower limit of detection of this method is 0.5μg, the sampling volume is 600L, and the minimum detection concentration is 0.8μg/m3. UDC614.78:613
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GB8912—88
1.3 Determination range
Using 5ml absorption liquid, the linear range of this method is 0.5~20μg. According to the sampling conditions (600L) specified in this method, the measurable concentration range is 0.8~33.3μg/m3.
1.4 Interference and elimination
Since this method uses the method of converting the chlorine into arsenic gas for determination, a large number of interference factors are avoided. 100μg of mercury, manganese, copper, nickel, cobalt, lead and iron, 50μg has no interference, trivalent bismuth, tetravalent selenium, hexavalent chromium have negative interference on the reaction when the content is large, but when the content is less than 30μg, 10μg and 20μg respectively, there is no interference. The properties of antimony are very similar to those of the monument. When the sample contains arsenic, SbH can be formed, which forms color with the absorption liquid, making the result higher, but when the content is less than 50μg, it will not interfere with the determination. 2 Principle
Arsenide collected on filter paper impregnated with polyethylene pyridine oxide is dissolved in hydrochloric acid, and then reduced to arsenic hydrogen by the added potassium iodide, stannous chloride and zinc particles, and then reacts with the chloroform solution of silver triethylamine diethylaminodithiocarboxylate to generate red colloidal silver for colorimetric quantification.
3 Reagents and materials
The purity of the reagents used in this method should be analytically pure. All experimental water is arsenic-free distilled water or deionized water, and the water quality has a conductivity of less than 1.0uS/cm at 25℃.
3.1 Polyethylene pyridine oxide [(C,H,C,H,N=O)n, n=3000 μL, also known as gram silane, referred to as P204). 3.2 Propylene glycol.
3.3 Quantitative filter paper: slow (or medium) fixed filter paper, diameter 40mm, each piece of arsenic content shall not exceed 0.1μg. 3.4 Impregnated filter paper: weigh 10g polyethylene pyridine oxide and measure 10ml triol solution in 100ml water to make the impregnation solution, immerse the filter paper with a diameter of 40mm in the solution, take it out after 6 hours, place it on a clean glass plate, put it in a convection box, dry it with an infrared lamp, and store the impregnated filter paper in a glass bottle for use. 3.53+2 hydrochloric acid solution. Www.bzxZ.net
3.615% potassium iodide solution.
Approved by the Ministry of Health of the People's Republic of China on February 23, 1988398
Implemented on December 1, 1988
GB8912-88
3.740% stannous chloride solution: weigh 40g stannous chloride (SnC1, ·2H,O) and dissolve it in 50ml concentrated hydrochloric acid, add water to 100ml. 3.8 Zinc-free particles: about 15 particles per gram.
3.9 Lead acetate cotton: soak the absorbent cotton with 10% lead acetate solution, dry it and set it aside. When in use, fill it in the filter of the arsenic hydrogen generation and absorption device.
3.10 Silver diethylaminodithiocarboxylate-triethylamine-chloroform solution: weigh 0.25g silver diethylaminodithiocarboxylate, dissolve it with a small amount of chloroform, add 1.0ml triethylamine (or triethanolamine), dilute it to 100ml with chloroform, leave it overnight, if there is a precipitate, filter it and store it in a brown bottle. 3.11 Standard solution: accurately weigh 0.1320g arsenic trioxide dried at 105℃F for 2h, dissolve it in 2ml 1mol/L sodium hydroxide solution, add 50ml water, then add 2ml 1mo1/L hydrochloric acid solution, transfer it to a 100ml volumetric flask, add water to the scale, this solution 1ml = 1mg arsenic. Dilute it with water to make a standard solution of 1.0ml = 10μg arsenic before use. 4 Instruments and equipment
4.1 Filter paper sampling clamp: diameter 40mm (see Figure 1). 4$34
Figure 1 Filter paper sampling clip
1-Top cover; 2-Pressure ring, 3-Base
4.2 Constant flow sampling pump: Under sampling conditions, the maximum air flow can reach 15L/min, and the flow is stable and adjustable. The constant flow error is less than 2%.
4.3 Flow meter: 2~20L/min.
4.4 Stoppered colorimetric tube: 10ml, inner diameter 8mm. 4.5 Arsenic oxide generation and absorption device (see Figure 2). 399
GB8912—-88
Figure 2 Arsenic hydrogen generation and absorption device
1-Hydrogen generation bottle (150ml conical flask), 2-Filter filled with lead acetate cotton; 3-Gas guide tube: 4-10ml colorimetric tube (diameter 8mm) 4.6 Constant temperature water bath: The temperature control accuracy is ±1℃. 4.7 Spectrophotometer, 520nm, slit less than 20nm. 5 Sampling
Place the filter paper soaked with polyethylene pyridine oxide in the sampling clamp and clamp it, and sample for 60 minutes at a flow rate of 10L/min. Before and after sampling, the flow rate of the sampling system should be calibrated with a soap film flowmeter, and the error should not exceed 5%. Record the temperature and atmospheric pressure of the sampling point. 6 Operating steps
6.1 Drawing of the standard curve
6.1.1 Accurately aspirate 0.0, 0.10, 0.30, 0.50, 1.00, 1.50, 2.00ml of the monument standard solution and 7 pieces of impregnated filter paper respectively, and place them in the arsenic hydrogen generating bottle, add water to 70ml each, and add 30ml of 3+2 hydrochloric acid solution. 6.1.2 Add 2 ml of 15% potassium iodide solution and 0.4 ml of stannous chloride solution, mix well, let stand for 15 minutes, add 5 g of arsenic-free zinc particles, and immediately connect the filter filled with lead acetate cotton and a colorimetric tube containing 5 ml of diethylaminodithiocarboxysilver-triethylamine-chloroform solution. Let the reaction take 1 hour. Add chloroform to each tube to make up to 5 ml. Use a 1 cm colorimetric IIIl to measure the absorbance at a wavelength of 520 nm and draw a standard curve using absorbance versus arsenic content (μg). 6.2 Sample determination
Use a pair of shiny, rust-free scissors to cut the filter paper after collecting the sample into small pieces and place them in an arsenic hydrogen generating bottle. At the same time, take the impregnated filter paper of the same specification and size as a blank control, add 30ml of 3+2 hydrochloric acid solution to each, place in a 60℃ constant temperature water bath for 12.5h (or place at room temperature overnight), take out, cool to room temperature, add 70ml of water, and proceed as follows in step 6.1.2 of drawing the standard curve, measure the absorbance, check the standard curve, and obtain the arsenic content (μg). 7 Result calculation
7.1 Convert the sampling volume into the sampling volume under standard conditions according to formula (1). Vo=V
Where: V
converted into the sampling volume under standard conditions, L; p
sampling volume, L,
GB8912—88
T. —absolute temperature of standard state, 273K; t-temperature of sampling point during sampling, °C
po atmospheric pressure of standard state, 101kPa (or 760mmHg):-atmospheric pressure of sampling point during sampling, kPa (or mmHg). 7.2 The mass concentration of arsenic in air is calculated according to formula (2). C
arsenic concentration, mg/m3
where: C
—arsenic content in sample filter paper solution, μg
b-arsenic content in blank filter paper solution, μg. 8 Precision and accuracy
(2)
8.1 Precision: When 2 and 6μg of arsenic are added to the impregnated filter paper, the relative standard deviations determined by this method are 8.3% and 3.3% respectively. 8.2 Accuracy: When 2 and 6 μg of chloramphenicol are added to the impregnated filter paper, the recoveries determined by this method are 88~110% and 92~100% respectively.
Additional Notes:
This standard was proposed by the Environmental Health Standards Subcommittee of the National Health Standards Technical Committee. This standard was drafted by the Guangdong Provincial Institute of Occupational Disease Prevention and Control. The main drafters of this standard are Ye Nengquan, Lu Zhanrong and Tong Yingfang. This standard is interpreted by the Environmental Health Monitoring Institute of the Chinese Academy of Preventive Medicine, the technical unit entrusted by the Ministry of Health. 401
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