GB/T 8913-1988 Hygienic standard for the determination of sulfur dioxide in the atmosphere of residential areas - Mercury tetrachloride - pararosaniline hydrochloride spectrophotometric method
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Scope of application
National Standard of the People's Republic of China
Hygienic determination method of sulfurdioxide in air of residential areas-Tetra-chloromercurate (TCM)-pararosanilinespectrophotometric method
This standard is applicable to the determination of sulfur dioxide mass concentration in the atmosphere of residential areas. 1.1 Sensitivity
When the final colorimetric volume is 25ml, 1μg sulfur dioxide should have an absorbance of 0.03. 1.2 Lower limit of detection
The lower limit of detection of this method is 0.75μg. When the sampling volume is 30L, the minimum detection concentration is 25μg/m3. 1.3 Concentration measurement range
UDC614.78:613
15:546.22
GB8913-88
Using 10ml sample solution, the linear range of this method is 0.8~27μg. According to the sampling conditions specified in this method, the measurable concentration range of 30~60min samples is 25~1000μg/m3, and the measurable range of 24h samples is 13~ 500μg/m3. 1.41 Interference and Elimination
This method has taken effective measures to eliminate various known interferences. Nitrogen dioxide is removed by adding aminosulfonic acid; ozone is decomposed by leaving it for 20 minutes before analysis; heavy metals are complexed and concealed with EDTA sodium salt and phosphoric acid. The presence of 60gFe3, 10ugMn2, 10μgCr3+, 10μgCu2+ and 22ug+ in 10ml sample solution does not interfere with this method. Hydrogen, sulfide and aldehydes do not interfere with the determination of sulfur oxide.
2 Principle
Sulfur oxide in the air is absorbed by potassium tetrachloride solution, and reacts with formaldehyde and pararosaniline hydrochloride (PRA) to produce purple-red. According to the depth of the generated color, colorimetric quantification is performed. 3 Reagents
The purity of the general reagents used should be analytical grade, and the reference reagents should be of high grade purity. All experimental water is redistilled water or deionized water. The water quality should have a conductivity of less than 1.0μS/cm at 25℃ and a pH of 6.0~7.2. 3.1 Absorption solution (0.04mol/L potassium tetrachloride solution) Weigh 10.86g chlorinated water, 5.96g potassium chloride, and 0.066g ethylenediaminetetraacetic acid-disodium salt and dissolve them in water, and dilute to 1000ml. The absorption solution is highly toxic and must be used with great care. When it comes into contact with the skin, it should be rinsed with water immediately. The liquid containing the absorption solution should be centrally treated. The treatment method is shown in the attached document. .
3.20.6% aminosulfonic acid solution
Weigh 0.6g aminosulfonic acid and dissolve it in 100ml water. This reagent should be prepared fresh every day. Approved by the Ministry of Health of the People's Republic of China on February 23, 1988 402
Implemented on December 1, 1988
3.30.2% solution
GB891388
Measure 1ml of formaldehyde with a content of 36%~38° and dilute it with water to 200ml. This reagent should be prepared fresh every day. 3.40.016% hydrochloric acid paraben solution
3.4.11mol/L hydrochloric acid solution: measure 86ml of concentrated hydrochloric acid (specific gravity about 1.19g/ml) and dilute it with water to 1000ml. 3.4.23mol/L phosphoric acid solution: measure 205ml of concentrated phosphoric acid (specific gravity about 1.69g/ml) and dilute it with water to 1000ml. 3.4.3 0.2% Rose Aniline Hydrochloride Preparation Solution: Accurately weigh 0.200g of rose aniline hydrochloride (PRA, the purity of which shall not be less than 95%, see Appendix A for purity test method) and dissolve it in 100ml of hydrochloric acid solution. 3.4.4 0.016% Rose Aniline Hydrochloride Preparation Solution: Accurately weigh 20ml of the preparation solution into a 250ml volumetric flask, add 25ml of phosphoric acid solution, and dilute to the mark with water. This solution can be stored in a dark place for six months. The amount of each drop should be corrected according to the PRA purity test result, subtracting the purity percentage from 100%, and adding 0.2ml of the preparation solution for every 1% shortfall.
3.5 Sulfur dioxide standard solution
3.5.1 Sodium sulfate standard preparation solution: Weigh 0.200g sodium sulfate (NazSO,) and dissolve it in 1250ml of freshly boiled and cooled water. This solution contains 320-400μg sulfur dioxide per liter. The accurate concentration is calibrated according to the method in Appendix B. The accurate concentration of sulfur dioxide is calculated by adding excess iodine solution to oxidize it and then adding sodium thiosulfate standard solution. 3.5.2 Sodium sulfate standard working solution: According to the calibration calculation results, dilute the standard preparation solution with absorption liquid to a standard working solution containing 5μg sulfur dioxide per ml.
3.6 Sulfur dioxide permeation tube
Purchase an accurately calibrated sulfur dioxide permeation tube, which is required to have a permeability between 0.25 and 1.5μg/min at 25 or 30±0.1℃. 4 Instruments and equipment
4.1 Sampling device
4.1.1 Tube: The air inlet duct in front of the sampling tube should be made of materials such as polytetrafluoroethylene, polyolefin or borosilicate glass. 4.1.2 Absorption tube: According to different sampling cycles, it can be divided into two types. 4.1.2.1 Porous glass plate absorption tube (Figure 1): Used for 30~60min sample collection, can hold 10ml absorption liquid. The filter plate resistance of the absorption tube is 30~40mmHg (flow rate 500ml/L), and the sieve plate bubbles should be evenly dispersed. 17.5
Porous glass plate absorption tube
GB8913-88
4.1.2.2 Flushing sampling tube (Figure 2): Used for 24h sample collection, can hold 50ml absorption liquid, the nozzle aperture is between 0.37~0.41mm, and the distance between the nozzle and the bottom of the absorption tube should be 6mm. 5
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Figure 2 flushing sampling tube
4.1.3 protective filter; used to filter particulate matter in the sampling system to avoid affecting the use of the rotary flow meter. 4.1.4 flow metering device: rotary flow meter or other flow meter can be used. The flow value of 30~60min sample is 0.50L/min, and the flow value of 24h sample is 0.20L/min. The electromembrane flow meter should be calibrated for accurate flow before and after use. 4.2 spectrophotometer: a spectrophotometer that can measure absorbance at a wavelength of 550nm and a slit size of 20nm. 4.3 analysis day: sensitivity is 0.1mg.
constant temperature water bath (0～37℃): the temperature should be controlled to reach 22±1℃, used for sample color development. 4.4
4.5Super constant temperature water bath: the temperature should be controlled at 25±0.1℃ or 30±0.1℃, for permeation gas distribution. 4.6Constant flow pump: under sampling conditions, the maximum flow can reach 1L/min, and the H flow rate is stable and adjustable. The flow error is less than 2%. Before sampling and sampling, the flow of the sampling system should be accurately calibrated by an electromembrane meter. 5Sampling
5.130~60min sample
Use a porous plate absorption tube with 10ml absorption liquid inside, and sample at a flow rate of 0.5Lmin for 30 or 60min5.224h sample
Use a flushing sampling tube with 50ml absorption liquid inside, and sample at a flow rate of 0.20l/min for 24h. 404
GB8913—88
Before sampling, the sampling device should be connected according to Figure 3, and the sampling system connection should be checked to see if it is correct, whether there is gas phenomenon or other faults. During sampling, the absorption liquid should be protected from sunlight, and the absorption liquid temperature must be maintained between 5 and 20°C. The flow error before and after sampling shall not be greater than 5%.
Record the temperature and atmospheric pressure of the sampling point in time. Sampling bar
6 Operation steps
6.1 Drawing standard curve
Absorption tube
Protective filter material
Sulfur dioxide sampling series
6.1.1 Prepare standard curve with sulfur dioxide standard solution Vapor flow meter
6.1.1.1 Use six 25ml volumetric flasks and prepare the standard series with sulfur dioxide standard solution according to the table below. Bottle
Standard 1 as liquid, ml
Absorption liquid, ml
Sulfur dioxide content, g
6.1.1.2 Add 1.00ml0.6%aminosulfonic acid solution to each bottle of the standard series, mix well, and let stand for 10 minutes, then accurately add 2.00ml0.2% formaldehyde solution and 5mlo.0.16% pararosaniline hydrochloride solution, add water to the scale, mix well, and place in a constant temperature water bath at 22±1℃ for 30min. Www.bzxZ.net
After preheating the spectrophotometer, use 1cm colorimetric IIIl, wavelength 548nm, and water as reference to determine the absorbance of each bottle of solution. Draw a standard curve with sulfur oxide content as the horizontal axis and absorbance as the vertical axis, or use the least squares method to find the best fitting curve. The slope of the standard curve 6 should be 0.0300.002 absorbance/μg sulfur oxide, the intercept a should be less than 0.170, and the range of variation should be less than 0.03 absorbance.
The reciprocal of the residual slope b is used to obtain Bs as the calculation factor for sample determination. 6.1.2 Drawing a standard curve with sulfur oxide standard gas For the device and method of preparing standard gas with permeation tube, refer to GB5275-85 "Preparation of mixed gas for gas analysis standard permeation method".
6.1.2.1 Place the sulfur oxide permeation tube with known permeability in the gas generating bottle and keep it at a constant temperature for more than 24 hours at the temperature of the calibrated permeability (generally 30.0±0.1℃). Use pure nitrogen at a small flow rate (about 250ml/min) through the gas preheating tube and the gas generating bottle, send the permeated sulfur oxide into the gas dilution bottle, mix and dilute it with purified air, adjust the flow ratio of nitrogen and air to obtain sulfur oxide standard gas of different concentrations, the concentration of which is calculated as follows: C
Wherein: C-
GB8913-88
Concentration of sulfur dioxide standard gas, ug/m3;
P—Permeability of sulfur oxide permeation tube, μg/minF—Flow rate of nitrogen under standard conditions, L/min; Flow rate of dilution air under standard conditions, L/mineF
Connect various concentrations of standard gases into the sampling series, and sample according to the conventional sampling method. Generally, there are no less than four concentration groups within the measurable concentration range of this method, and use zero concentration gas as a blank control. 6.1.2.2 Transfer the samples of standard gas of each concentration into a 25ml volumetric flask, measure the absorbance of standard gas of various concentrations according to the method described in 6.1.1.2, draw a standard curve with absorbance versus concentration of sulfur dioxide standard gas (ug/m3), and the inverse of the slope 6 B is the calculation factor for sample determination.
6.2 Sample analysis
6.2.1 After sampling, if particulate matter is found in the sample solution, it should be removed by centrifugation. For 30~60min samples, the sample solution in the absorption tube can be directly transferred into a 25ml volumetric flask, and the absorption tube can be washed twice with 5ml water, and the washing liquid is combined in the volumetric flask and placed for 20min to allow ozone to completely decompose before analysis.
24h samples: Make up the sample to 50ml with water, mix well, take 10ml into a 25ml volumetric flask, and place for 20min before analysis. Each sample should be measured in parallel, and the error should be less than 0.03 absorbance. 6.2.2 Take another 10ml (unsampled) absorption solution and place it in a 25ml volumetric flask for reagent blank determination, and prepare a standard control tube containing 10μg sulfur dioxide for quality control in sample analysis. 6.2.3 The sample solution, reagent blank and standard control tube are measured according to the operating steps of drawing the standard curve in 6.1.1.2, and the sample absorbance A, reagent blank absorbance A. and standard quality control tube absorbance As are recorded respectively. If A, A. and As are within the quality control limit, the data of sample analysis is valid. When drawing the quality control chart, the control range of the quality control tube is determined by the concentration. For example, the error of the quality control tube containing 10μg sulfur dioxide is 7.5%, the control limit of the blank tube is ±0.03 absorbance, and the absorbance of all blank tubes is less than 0.17. If it is not within the control limit, the cause should be checked and the sample should be analyzed again, and the original sample reading is invalid. 7 Calculation
7.1 Calculate the sampling volume to the sampling volume under standard conditions according to formula (2): Vo=Vx
-sampling volume under standard conditions, L;
sampling volume, obtained by multiplying the sampling flow rate by the sampling time, L; T-absolute temperature under standard conditions, 273K;
pg-atmospheric pressure under standard conditions, 101kPa (or 760mmHg); p-atmospheric pressure at the time of sampling, kPa (or mmHg); air temperature at the time of sampling, °C.
7.2 Air: sulfur dioxide concentration
7.2.1 When preparing the standard curve with sulfur dioxide standard solution, calculate the sample concentration using formula (3). Sulfur dioxide (μg/m3)
Where: A—absorbance of a sample:
—absorbance of a reagent blank:
—calculation factor, ug/absorbance
10\-—μg/L converted to ug/m
(A- A) ×Bs× 103
D—dilution factor (1 for 30~60min sample, 5 for 24h sample). 406
GB8913—88
7.2.2 When preparing a standard curve using sulfur dioxide standard gas, use formula (4) to calculate the sample concentration. Sulfur dioxide (μg/m3) = (A-Ag) x BgWhere: A—absorbance of sample;
As—absorbance of reagent blank;
Bg——calculation factor, μg/(m3.absorbance). 8 Precision and accuracy
For the analysis of standard samples, the coefficient of variation is less than 5% at 5g/10ml absorption solution. When the concentration of the standard is 100-200μg/m3, the relative error between the measured value and the standard value is less than 20%. 407
A.1 Purity determination of pararosaniline hydrochloride
GB8913-88
Appendix A
Purification and purity determination of pararosaniline hydrochloride (supplement)
Parrosaniline hydrochloride should be determined for purity according to the following method. If the purity does not meet the requirements, it should be purified according to A.2. A.1.1 Blank value check
The 0.016% pararosaniline hydrochloride working solution prepared according to 3.4.4 is used for reagent blank determination (see 6.2.2). The absorbance should be less than 0.17. A.1.2 Purity check
Measure 1 ml of the stock solution of pararosaniline hydrochloride (see 3.4.3) and dilute it to 100 ml with water. Take 5 ml of this dilution in a 50 ml volumetric flask, add 5 ml of 1.1 mol/L acetic acid-acetate buffer, dilute it to the mark with water, let it stand for 1 hour, and measure the absorbance at 540 nm with a 1 cm colorimetric III.
Calculate the percentage of pararosaniline hydrochloride using the following formula: Pararosaniline hydrochloride (%) ×
Where: A - absorbance measured according to this method; 21300 -
Calculation constant when the slit of the spectrophotometer is 10 nm; - the number of milligrams of pararosaniline hydrochloride in 50 ml of the stock solution. A × 21300
According to this method, the percentage of pararosaniline hydrochloride should not be less than 95%. A.2 Purification of pararosaniline hydrochloride
A.2.1 Take 100 ml of n-butanol and 1 mol/L hydrochloric acid, respectively, and place them in a 250 ml separatory funnel. Shake for 3-5 minutes to allow them to dissolve and reach equilibrium, and then separate them for later use.
A.2.2 Weigh 0.1 g of pararosaniline hydrochloride to be tested into a 100 ml beaker, add 50 ml of the balanced hydrochloric acid, dissolve and leave for a few minutes, then transfer to a 125 ml separatory funnel.
A.2.3 Add 50ml of balanced n-ethanol and shake for 2-3min to transfer the purple impurities into the organic phase. A.2.4 Place the aqueous phase in another separatory funnel and add 20ml of half-balanced n-ethanol to extract 1-2 times to remove impurities in the dye.
A.2.5 After the extraction, filter the aqueous phase through a cotton plug, collect the filtrate in a 50ml volumetric flask, and dilute to the mark with 1mol/L hydrochloric acid to prepare the stock solution. This stock solution should be red-yellow. 408
B.1 Reagents
GB8913-88
Appendix B
Standardization method for sulfur dioxide concentration in sulfite solution (supplement)
B.1.1 0.05mol/L iodine stock solution: weigh Take 40g potassium iodide (KI) and dissolve it in 25ml water, then add 12.7g iodine (I2). After the iodine is completely dissolved, dilute it to the mark in a 1L volumetric flask with water, transfer it to a brown bottle, and store it in a dark place. B.1.2 0.005mol/L iodine 1. Preparation solution: measure 50ml iodine stock solution, add 10g potassium iodide, and dilute it to the mark with water in a 500ml volumetric flask. Store it in a brown bottle. This 1. Preparation solution should be freshly prepared before use. B.1.3 0.05% starch indicator: weigh 0.5g soluble starch, add 5ml water to make a paste, then pour in 100ml boiling water, continue to boil, purify until transparent, and use it after cooling. B.1.4 0.1mol/L potassium iodate standard solution: accurately weigh 3.5g of high-purity potassium iodate (KIO3) dried at 105℃F.5667g, dissolve in freshly boiled and cooled water, transfer to a 1L volumetric flask, and dilute to the mark with water. B.1.5 0.1mol/L sodium thiosulfate standard solution (NazS,O: 5H,O): dissolve 25g sodium thiosulfate in 1000ml freshly boiled and cooled water, add 10.1g sodium carbonate peroxide, and calibrate its accurate concentration after leaving it for one day. Calibration method: accurately measure 25ml 0.1mol/L potassium iodate solution (see B.1.4) and place it in a 250ml iodine volumetric flask, add 75ml freshly boiled and cooled water, add 3g potassium iodide and 10ml 1mol/L hydrochloric acid, shake well, place in a dark place and let stand for 5min, add sodium thiosulfate solution (see B.1.5) until it turns light yellow, add 1ml 0.5% starch indicator to turn blue, and continue to add sodium thiosulfate solution until the blue just disappears, which is the end point. Record the amount of sodium thiosulfate solution (V) in milliliters. Use formula (B1) to calculate its exact concentration: Sodium thiosulfate concentration (mol/L) =
(B1)
Perform two parallel titrations. The difference between the sodium thiosulfate solutions used cannot exceed 0.05ml, otherwise the parallel determination should be repeated. B.1.6 0.01mol/L sodium thiosulfate standard 1. Make a solution: Use a pipette to accurately pipette 100ml of the sodium thiosulfate standard stock solution with a concentration of 0.1mol/L after calibration into a 1000ml volumetric flask, and dilute to the mark with freshly boiled and cooled water. This solution is unstable and must be prepared freshly before use.
B.2 Calibration of sodium sulfite standard solution
Take two 250ml iodine volumetric flasks, mark them "A" and "B" respectively, add 50ml iodine working solution (see B.1.2) to each flask, accurately add 25ml sodium sulfite standard stock solution (see 3.5.1) to bottle "A", add 25ml water to bottle "B", mix well and let stand for 5min, titrate with 0.01mol/L sodium thiosulfate standard working solution (see B.1.6) until light yellow, add 1ml 0.5% starch indicator, and continue to titrate until the blue color just disappears, record the amount of sodium thiosulfate solution used, and calculate the sulfur dioxide content using formula (B2).
Sulfur dioxide concentration (μg/ml) = _32 000 (BA) × M25
Where: A-ml of sodium thiosulfate titrated with sample; B——ml of sodium thiosulfate titrated with blank; M-accurate concentration of sodium thiosulfate, mol/L; 25——ml of sodium thiosulfate standard stock solution; 1ml of 1mol/L sodium thiosulfate is equivalent to micrograms of sulfur dioxide. 32000-
Second half-row titration, the error should be less than 0.05ml, otherwise recalibrate. (B2)
GB8913-88
Treatment of mercury-containing waste liquid
(reference)
This appendix introduces the recovery method of mercury in waste liquid to avoid environmental pollution. c.1 Reagents
C.1.1 40% sodium hydroxide solution: weigh 400g of sodium hydroxide and dissolve it in 1000ml of water. C.1.2 30% hydrogen peroxide solution.
C.1.3 Sodium sulfide (Na2S·9H,O).
C.2 Method
Use a 50L plastic bucket to collect the waste liquid after sample analysis. When the waste water volume reaches about 40L, treat it as follows. Mix the waste liquid by aeration, add 100ml of sodium hydroxide (to neutralize the waste liquid), and then add 100g of sodium sulfide. After mixing for 10 minutes, slowly add 400ml of hydrogen peroxide. After standing for 24 hours, extract the supernatant and discard it. Additional remarks:
This standard was proposed by the Environmental Sanitation Standard Subcommittee of the National Sanitation Standard Technical Committee. This standard was drafted by the health and epidemic prevention stations of Shanghai, Beijing, Xi'an, Shenyang, Guangzhou and the Environmental Health Monitoring Institute of the Chinese Academy of Preventive Medicine.
The main drafters of this standard are Zhang Genfa and Song Ruijin. 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.
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