HJ 482-2009_English: PDF (HJ482-2009)
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Ambient air. Determination of sulfur dioxide. Formaldehyde absorbing-pararosaniline spectrophotometry
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HJ 482-2009
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Standards related to: HJ 482-2009
| Standard ID | HJ 482-2009 (HJ482-2009) | | Description (Translated English) | Ambient air. Determination of sulfur dioxide. Formaldehyde absorbing-pararosaniline spectrophotometry | | Sector / Industry | Environmental Protection Industry Standard | | Classification of Chinese Standard | Z15 | | Classification of International Standard | 13.040 | | Word Count Estimation | 12,135 | | Date of Issue | 2009-09-27 | | Date of Implementation | 2009-11-01 | | Older Standard (superseded by this standard) | GB/T 15262-1994 | | Drafting Organization | Shenyang Municipal Environmental Monitoring Center Station | | Administrative Organization | Ministry of Environment Protection | | Regulation (derived from) | Department of Environmental Protection Notice No. 47 of 2009 | | Summary | This standard specifies the determination of sulfur dioxide in ambient air formaldehyde absorption pararosaniline method. This standard applies to the determination of sulfur dioxide in ambient air. |
HJ 482-2009
Ambient air.Determination of sulfur dioxide.Formaldehyde absorbing-pararosaniline spectrophotometry
HJ
National Environmental Protection Standard of the People's Republic
Replace GB/T 15262-94
Determination of ambient air sulfur dioxide
Formaldehyde absorption-pyro-aniline spectrophotometry
Ambient air-Determination of sulfur dioxide
-Formaldehyde absorbing-pararosaniline spectrophotometry
Published on.2009-09-27
2009-11-01 Implementation
Ministry of Environmental Protection released
Ministry of Environmental Protection
announcement
No. 47 of.2009
In order to implement the "Environmental Protection Law of the People's Republic of China", protect the environment, and protect human health, we now approve the measurement of water quality polycyclic aromatic hydrocarbons.
Eighteen standards, such as fixed liquid extraction and solid phase extraction high performance liquid chromatography, are national environmental protection standards and are released.
The standard name and number are as follows.
I. Determination of Polycyclic Aromatic Hydrocarbons by Liquid-Liquid Extraction and Solid Phase Extraction High Performance Liquid Chromatography (HJ 478-2009);
2. Determination of nitrous oxides (nitrogen oxides and nitrogen dioxide) - Determination of naphthalene diamine hydrochloride spectrophotometric method (HJ 479-
2009);
III. Determination of Fluoride in Ambient Air Filtration of Fluoride Ion Selective Electrode Method (HJ 480-2009);
IV. Determination of fluoride in ambient air Determination of fluoride ion-selective electrode method for lime filter paper (HJ 481-2009);
6. Determination of Sulfur Dioxide in Ambient Air - Tetrachloromercury Salt Absorption - Pararosaniline Spectrophotometry (HJ 483-2009);
VII. Determination of water content cyanide volumetric method and spectrophotometry (HJ 484-2009);
VIII. Determination of copper in water quality by diethyldithiocarbamate spectrophotometry (HJ 485-2009);
IX. Determination of copper in water quality 2,9-Dimethyl-1,10 phenanthroline spectrophotometry (HJ 486-2009);
X. Determination of Fluoride in Water Quality by Spectrophotometric Method of Zirconium Sulfate Sulfate (HJ 487-2009);
XI. Determination of Fluoride in Water Quality Fluorescence Spectrophotometry (HJ 488-2009);
XII. Determination of Silver in Water Quality 3,5-Br2-PADAP Spectrophotometry (HJ 489-2009);
XIII. Determination of Silver in Water Quality by Cadmium Reagent 2B Spectrophotometry (HJ 490-2009);
XIV. Determination of Total Chromium in Soils by Flame Atomic Absorption Spectrophotometry (HJ 491-2009);
15. Air Quality Vocabulary (HJ 492-2009);
XVI. Technical Regulations for the Preservation and Management of Water Quality Samples (HJ 493-2009);
17. Water Quality Sampling Technical Guidance (HJ 494-2009);
18. “Technical Guidance for the Design of Water Quality Sampling Plans” (HJ 495-2009).
The above standards have been implemented since November 1,.2009 and published by the China Environmental Science Press. The standard content can be found on the website of the Ministry of Environmental Protection.
From the date of implementation of the above standards, the following 20 national environmental protection standards approved and issued by the former National Environmental Protection Agency shall be abolished.
The exact name and number are as follows.
1. "Determination of six specific polycyclic aromatic hydrocarbons in water quality by high performance liquid chromatography" (GB 13198-91);
2. Determination of nitrogen oxides in air quality - Determination of naphthylethylenediamine hydrochloride (GB 8969-88);
3. "Saltzman method for determination of nitrogen oxides in ambient air" (GB/T 15436-1995);
4. Determination of the concentration of fluoride in ambient air, filter membrane and fluoride ion selective electrode method (GB/T 15434-1995);
V. Determination of Fluoride in Ambient Air Lime Filter Paper · Fluoride Ion Selective Electrode Method (GB/T 15433-1995);
6. Determination of Sulphur Dioxide in Ambient Air - Formaldehyde Absorption - Pararosaniline Spectrophotometry (GB/T 15262-94);
VII. Determination of Air Quality, Sulfur Dioxide, Tetrachloromercury Salt - Pararosaniline Hydrochloride Colorimetric Method (GB 8970-88);
VIII. Determination of Cyanide in Water Quality Part I Determination of Total Cyanide (GB 7486-87);
IX. Determination of Cyanide in Water Quality Part 2 Determination of Cyanide (GB 7487-87);
X. Determination of copper in water quality by diethyldithiocarbamate spectrophotometry (GB 7474-87);
XI. Determination of Copper in Water Quality 2,9-Dimethyl-1,10-phenanthroline Spectrophotometric Method (GB 7473-87);
Twelve, "Determination of Fluoride in Water Quality, Zirconium Sulfonic Acid Visual Colorimetric Method" (GB 7482-87);
XIII. Determination of Fluoride in Water Quality Fluorescence Spectrophotometry (GB 7483-87);
XIV. Determination of Silver in Water Quality, 3,5-Br2-PADAP Spectrophotometry (GB 11909-89);
Fifteen, "Measurement of mercury in water, cadmium reagent 2B spectrophotometry" (GB 11908-89);
XVI. Determination of Total Chromium in Soil Quality by Flame Atomic Absorption Spectrophotometry (GB/T 17137-1997);
17. Air Quality Vocabulary (GB 6919-86);
18. Technical Regulations for the Preservation and Management of Water Samples (GB 12999-91);
Nineteen, "Water Quality Sampling Technical Guidance" (GB 12998-91);
20. Technical Regulations for the Design of Water Quality Sampling Plans (GB 12997-91).
Special announcement.
September 27,.2009
Content
Foreword..iv
1 Scope..1
2 Method principle..1
3 interference and elimination.1
4 Reagents and materials.1
5 instruments and equipment.3
6 Sample Collection and Storage..3
7 Analysis steps..3
8 results indicate that. .4
9 precision and accuracy..4
10 Quality Assurance and Quality Control.5
Appendix A (informative appendix) Desalination and purification of para-aniline.6
Foreword
To protect the environment and protect people in order to implement the Environmental Protection Law of the People's Republic of China and the Law of the People's Republic of China on the Prevention and Control of Air Pollution
This standard is established for the determination of sulfur dioxide in air.
This standard specifies the formaldehyde absorption-pararosaniline spectrophotometric method for the determination of sulfur dioxide in ambient air.
This standard is for the determination of sulfur dioxide in ambient air - formaldehyde absorption - pararosaniline spectrophotometry (GB/T 15262-94)
Revision.
This standard was first published in.1994. The original standard drafting unit was the Shanghai Environmental Monitoring Center. This is the first revision.
The main revisions are as follows.
- clarify the standard detection limits and measurement range;
- Revised the concentration of the iodine solution and sodium thiosulfate solution used to calibrate the sulfur dioxide standard solution;
-- Added field blank test;
-- Improve the calculation formula of the results;
-- Added quality assurance and quality control provisions. Increased requirements for the quality of the absorption tube of the porous glass plate; emphasis on temperature versus sampling efficiency
The effect of the rate; the requirement for the slope of the calibration curve is relaxed.
This standard is the national environmental protection standard approved by the former Environmental Protection Agency on October 26,.1994.
Determination of sulphur dioxide in airborne formaldehyde absorption - pararosaniline spectrophotometry (GB/T 15262-94) abolished.
This standard was formulated by the Science and Technology Standards Department of the Ministry of Environmental Protection.
This standard is mainly drafted by. Shenyang Environmental Monitoring Center Station.
This standard was approved by the Ministry of Environmental Protection on September 27,.2009.
This standard has been implemented since November 1,.2009.
This standard is explained by the Ministry of Environmental Protection.
Iv
Determination of ambient air sulfur dioxide
Formaldehyde absorption-pyro-aniline spectrophotometry
1 Scope of application
This standard specifies the formaldehyde absorption-pararosaniline spectrophotometric method for the determination of sulfur dioxide in ambient air.
This standard applies to the determination of sulfur dioxide in ambient air.
When 10 ml of absorption solution is used and the sampling volume is 30 L, the detection limit of sulfur dioxide in the air is determined to be 0.007 mg/m3.
The limit is 0.028 mg/m3 and the upper limit of determination is 0.667 mg/m3.
When 50 ml of absorption solution is used, the sampling volume is 288 L, and the test volume is 10 ml, the detection limit of sulfur dioxide in the air is determined as
0.004 mg/m3, the lower limit of determination is 0.014 mg/m3, and the upper limit of determination is 0.347 mg/m3.
2 Principle of the method
After the sulfur dioxide is absorbed by the formaldehyde buffer solution, a stable methylolsulfonic acid addition compound is formed, and sodium hydroxide is added to the sample solution.
The addition compound is decomposed, and the released sulfur dioxide reacts with pararosaniline and formaldehyde to form a purple-red compound, which is spectrophotometer.
The absorbance is measured at a wavelength of 577 nm.
3 interference and elimination
The main interferents in this standard are nitrogen oxides, ozone and certain heavy metal elements. After being sampled for a period of time, the ozone can be decomposed by itself;
Adding sodium sulfamate solution can eliminate the interference of nitrogen oxides; adding phosphoric acid and cyclohexanediaminetetraacetic acid disodium salt to the absorption solution can eliminate or reduce
Interference from certain metal ions. 10 ml sample solution contains 50 μg of metal ions such as calcium, magnesium, iron, nickel, cadmium, copper and 5 μg of divalent manganese
In the case of ions, there is no interference with the measurement of the method. When the 10 ml sample solution contains 10 μg of divalent manganese ions, the absorbance of the sample can be made.
Reduced by 27%.
4 reagents and materials
Analytically pure reagents that meet national standards are used for analysis, and experimental water is newly prepared distilled water or equivalent purity unless otherwise stated.
Water.
4.1 Potassium iodate (KIO3), excellent grade, dried at 110 ° C for 2 h.
4.2 Sodium hydroxide solution, c (NaOH) = 1.5 mol/L. Weigh 6.0 g NaOH, dissolved in 100 ml of water.
4.3 Cyclohexanediaminetetraacetic acid disodium solution, c (CDTA-2Na) = 0.05 mol/L. Weigh 1.82 g of trans 1,2-cyclohexanediaminetetraacetic acid
[(trans-1,2-cyclohexylenedinitrilo)tetraacetic acid, abbreviated as CDTA], add NaOH solution (4.2) 6.5 ml,
Dilute to 100 ml of water.
4.4 Formaldehyde buffer absorption stock solution. draw 36%~38% formaldehyde solution 5.5 ml, CDTA-2Na solution (4.3) 20.00 ml; weigh
2.04 g Potassium hydrogen phthalate dissolved in a small amount of water; combine the three solutions, dilute to 100 ml with water, and store in the refrigerator for 1 year.
4.5 Formaldehyde buffer absorption solution; dilute the formaldehyde buffer absorption stock solution (4.4) by 100 times with water. Available at the time of use.
4.6 Sodium sulfamate solution, ρ (NaH2NSO3)=6.0 g/L. Weigh 0.60 g of sulfamic acid [H2NSO3H] in a 100 ml beaker and add
4.0 ml of sodium hydroxide (4.2), stir well with water until completely dissolved, dilute to 100 ml, shake well. This solution is sealed for 10 days.
4.7 Iodine stock solution, c(1/2I2)=0.10 mol/L. Weigh 12.7 g of iodine (I2) in a beaker, add 40 g of potassium iodide and 25 ml of water, stir
Stir until completely dissolved, dilute to 1 000 ml with water, and store in a brown bottle.
4.8 Iodine solution, c(1/2I2)=0.010 mol/L. Take iodine stock solution (4.7) 50 ml, dilute with water to 500 ml, store in brown mouth
In the bottle.
4.9 Starch solution, ρ (starch) = 5.0 g/L. Weigh 0.5 g of soluble starch in a 150 ml beaker and make a paste with a small amount of water.
Slowly pour 100 ml of boiling water, continue to boil until the solution is clear, cool and store in the reagent bottle.
4.10 potassium iodate reference solution, c (1/6KIO3) = 0.100 0 mol/L. accurately weigh 3.566 7 g potassium iodate (4.1) dissolved in water, moved into
In a 1 000 ml volumetric flask, dilute with water to the mark and shake.
4.11 Hydrochloric acid solution, c (HCl) = 1.2 mol/L. Measure 100 ml of concentrated hydrochloric acid and add to 900 ml of water.
4.12 Standard stock solution of sodium thiosulfate, c(Na2S2O3)=0.10 mol/L. Weigh 25.0 g of sodium thiosulfate (Na2S2O3·5H2O), dissolve
In 1 000 ml of freshly boiled but cooled water, 0.2 g of anhydrous sodium carbonate was added and stored in a brown thin-mouth bottle.
If the solution is cloudy, it must be filtered.
Calibration method. Pipette three portions of 20.00 ml potassium iodate reference solution (4.10) into a 250 ml iodine flask and add 70 ml of new boil.
However, the cooled water, add 1g of potassium iodide, shake it to complete dissolution, add 10 ml of hydrochloric acid solution (4.11), immediately cover the stopper and shake.
After placing in the dark for 5 min, titrate the solution with sodium thiosulfate standard solution (4.12) to pale yellow, add 2 ml of starch solution (4.9), followed by
Continue to titrate until the blue color just fades to the end. The concentration of sodium thiosulfate standard solution is calculated according to formula (1).
C1=
0.100 0 20.00
× (1)
Where. c1--sodium thiosulfate standard solution concentration, mol/L;
V--Titration of the volume of sodium thiosulfate standard solution consumed, ml.
4.13 Sodium thiosulfate standard solution, c(Na2S2O3) ≈0.010 00 mol/L. Take 50.0 ml of sodium thiosulfate stock solution (4.12)
Dilute to the mark with freshly boiled but cooled water in a 500 ml volumetric flask and shake well.
4.14 Ethylenediaminetetraacetic acid disodium salt (EDTA-2Na) solution, ρ (EDTA-2Na)=0.50 g/L. Weigh 0.25 g of ethylenediaminetetraacetic acid
The sodium salt [C10H14N2O8Na2·2H2O] is dissolved in 500 ml of freshly boiled but cooled water. Available at the time of use.
4.15 sodium sulfite solution, ρ (Na2SO3) =1 g/L. Weigh 0.2 g sodium sulfite (Na2SO3) and dissolve in.200 ml EDTA-2Na (4.14)
In the solution, slowly shake to prevent oxygenation and dissolve. After 2 to 3 hours, it is calibrated. This solution is equivalent to 320-400 μg of dioxane per milliliter
Sulfur.
Calibration method.
a. Take 6 250 ml iodine bottles (A1, A2, A3, B1, B2, B3) and add 25 ml of ethylenediamine tetraethylene in A1, A2 and A3.
Acid di-sodium salt solution (4.14), add 25.00 ml of sodium sulfite solution (4.15) to B1, B2, B3, and add 50.0 ml of iodine solution respectively.
(4.8) and 1.00 ml of glacial acetic acid, cover the cap and shake well.
b. Immediately pipette 2.00 ml of sodium sulfite solution (4.15) into a 100 ml containing 40 to 50 ml of formaldehyde absorption solution (4.4).
In a volumetric flask, dilute to the mark with formaldehyde absorption solution (4.4) and shake well. This solution is a standard storage solution of sulfur dioxide at 4 to 5 ° C
Refrigerated for 6 months.
c.A1, A2, A3, B1, B2, B3 Six bottles are placed in the dark for 5 min, then titrated to a light yellow with sodium thiosulfate solution (4.13)
Color, add 5 ml of starch indicator (4.9), continue to titrate until the blue color just disappears. The difference in volume of sodium thiosulfate solution used for parallel titration
Should not be greater than 0.05 ml.
The mass concentration of the standard storage solution of sulfur dioxide (4.15 b) is calculated by equation (2).
ρ (SO2)=
0 2( ) 32.02 10 2.00
25.00 100
VV c− × × × × (2)
Where. ρ (SO2) - the concentration of sulfur dioxide standard stock solution, μg/ml;
0V - volume of sodium thiosulfate solution (4.13) used for blank titration, ml;
V - volume of sodium thiosulfate solution (4.13) used for sample titration, ml;
The concentration of c2--sodium thiosulfate solution (4.13), mol/L.
4.16 Sulfur dioxide standard solution, ρ (SO2) = 1.00 μg/ml. standard storage solution of sulfur dioxide (4.15 b) with formaldehyde absorption solution (4.5)
Dilute to a standard solution containing 1.0 μg of sulfur dioxide per ml. This solution is used to draw a standard curve and is refrigerated at 4 to 5 ° C to stabilize 1
Months.
4.17 Pararosaniline hydrochloride (referred to as PRA, ie, sub-magenta or magenta) stock solution. ρ (PRA) = 2.0 g/L.
Its purity should meet the quality requirements of the purification and testing methods of para-rosaniline (see Appendix A).
4.18 Pararosaniline hydrochloride solution, ρ (PRA)=0.50 g/L. Pipette 25.00 ml of pararosaniline stock solution (4.17) in 100 ml
In a volumetric flask, add 30 ml of 85% concentrated phosphoric acid, 12 ml of concentrated hydrochloric acid, dilute to the mark with water, shake well, and store overnight. Light-tight
Sealed.
4.19 Hydrochloric acid-ethanol cleaning solution. prepared by mixing three parts (1 4) hydrochloric acid and one part of 95% ethanol for cleaning colorimetric tubes and colorimetric
Dish.
5 Instruments and equipment
5.1 Spectrophotometer.
5.2 Porous glass plate absorption tube. 10 ml porous glass plate absorption tube for short time sampling; 50 ml porous glass plate absorption tube for 24 h connection
Continue sampling.
5.3 Constant temperature water bath. 0～40°C, the control precision is ±1°C.
5.4 with colorimetric tube. 10 ml.
The used colorimetric tubes and cuvettes should be washed with hydrochloric acid-ethanol cleaning solution (4.19) in time, otherwise the red color is difficult to wash.
5.5 Air sampler. A common air sampler for short-time sampling, with a flow range of 0.1 to 1 L/min, should have a thermal insulation device. use
The sampler continuously sampled at 24 h should have the functions of constant temperature, constant current, timing, and automatic control switch, and the flow range is 0.1-0.5 L/min.
5.6 Common instruments in general laboratories.
6 Sample collection and preservation
6.1 Short-time sampling. a porous glass plate absorption tube containing 10 ml of absorption liquid is used, and gas is collected at a flow rate of 0.5 L/min for 45 to 60 minutes. Suck
The liquid collection temperature is maintained in the range of 23 to 29 °C.
6.2 24 h Continuous sampling. The bottle was absorbed by a perforated glass plate containing 50 ml of absorption liquid and continuously sampled at a flow rate of 0.2 L/min for 24 h. absorb
The liquid temperature was maintained in the range of 23 to 29 °C.
6.3 Field blank. Take the sampling tube with the absorption liquid to the sampling site. Except for no gas production, the other environmental conditions are the same as the sample.
Note 1. Sunlight should be avoided during sample collection, transportation and storage.
Note 2. The 24 h continuous sampler placed in the chamber (the kiosk) should be connected to the air quality centralized sampling pipeline system to reduce the dioxide dioxide.
The loss of sulfur before it enters the absorption bottle.
7 Analysis steps
7.1 Drawing of the calibration curve
Take 16 10 ml plug colorimetric tubes, divided into two groups, A and B, each with 7 sets, corresponding to the number. Group A prepares a calibration series according to Table 1.
Table 1 Sulfur dioxide calibration series
Pipe number 0 1 2 3 4 5 6
Sulfur dioxide standard solution (1.00 μg/ml)/ml 0 0.50 1.00 2.00 5.00 8.00 10.00
Formaldehyde buffer absorption liquid/ml 10.00 9.50 9.00 8.00 5.00 2.00 0
Sulfur dioxide content/μg 0 0.50 1.00 2.00 5.00 8.00 10.00
Add 0.5 ml of sodium sulfamate solution (4.6) and 0.5 ml of sodium hydroxide solution (4.2) to each tube of group A and mix.
1.00 ml of PRA solution (4.18) was added to each tube of Group B.
Pour all the solutions of each tube of group A into the B tube with the corresponding number and containing the PRA solution, immediately add the mixture and place it in constant
Color development in a warm water bath. Absorbance was measured at a wavelength of 577 nm using a 10 mm cuvette with water as a reference. After blank correction
The absorbance of the tube is plotted on the ordinate, and the content of sulfur dioxide (μg) is plotted on the abscissa. The regression equation of the calibration curve is established by least squares method.
The difference between the color temperature and room temperature should not exceed 3 °C. According to the seasonal and environmental conditions, select the appropriate color temperature and color development time according to Table 2.
Table 2 color temperature and color development time
Color temperature/°C 10 15 20 25 30
Color development time/min 40 25 20 15 5
Settling time/min 35 25 20 15 10
Reagent blank absorbance A0 0.030 0.035 0.040 0.050 0.060
7.2 Sample determination
7.2.1 If there is turbidity in the sample solution, it should be removed by centrifugation.
7.2.2 Place the sample for 20 min to decompose the ozone.
7.2.3 Samples collected in a short time. Transfer the sample solution from the absorption tube into a 10 ml colorimetric tube and wash with a small amount of formaldehyde absorption solution (4.5).
The polyester absorption tube, the washing liquid is incorporated into the colorimetric tube and diluted to the marking line. Add 0.5 ml of sodium sulfamate solution (4.6), mix and let stand for 10 min.
Remove interference from nitrogen oxides. The following steps are plotted with the calibration curve.
7.2.4 Samples collected continuously for 24 h. Transfer the sample from the absorption bottle into a 50 ml volumetric flask (or colorimetric tube) with a small amount of formaldehyde absorption solution.
(4.5) Wash the absorption bottle and pour it into a volumetric flask (or colorimetric tube) and dilute to the mark with the absorption solution (4.5). Draw the appropriate volume of test
Sample (depending on the concentration) 2 to 10 ml in a 10 ml colorimetric tube, then dilute to the mark with the absorption solution (4.5), add 0.5 ml of ammonia
Sodium sulfonate solution (4.6), mix and let stand for 10 min to remove the interference of nitrogen oxides. The following steps are plotted with the calibration curve.
8 results are expressed
The mass concentration of sulfur dioxide in the air is calculated according to formula (3).
Sa
( )
(SO ) t
AA a V
b VV
ρ − −= ×× (3)
Where. ρ (SO2)--the mass concentration of sulfur dioxide in the air, mg/m3;
A--the absorbance of the sample solution;
A0--the absorbance of the reagent blank solution;
B--the slope of the calibration curve, absorbance/μg;
A--the intercept of the calibration curve (generally less than 0.005);
Vt--the total volume of the sample solution, ml;
Va--the volume of the sample taken during the measurement, ml;
Vs--converted to the standard sample size (101.325 kPa, 273 K), L.
The calculation results are accurate to three decimal places.
9 Precision and accuracy
9.1 precision
10 laboratories measured a uniform standard sample of sulfur dioxide with a concentration of 0.101 μg/ml, and the relative standard deviation of repeatability was less than 3.5%.
The current relative standard deviation is less than 6.2%.
10 laboratories measured a uniform standard sample of sulfur dioxide with a concentration of 0.515 μg/ml, and the relative standard deviation of repeatability was less than 1.4%.
The current relative standard deviation is less than 3.8%.
9.2 Accuracy
105 actual samples with concentrations ranging from 0.01 to 1.70 μg/ml were measured, and the recoveries ranged from 96.8% to 108.2%.
10 Quality Assurance and Quality Control
10.1 The resistance of the absorption tube of the porous glass plate is 6.0 kPa±0.6 kPa, and the 2/3 glass plate area is evenly foamed, and no air bubbles escape at the edges.
10.2 When the temperature of the absorption liquid at the time of sampling is 23 to 29 ° C, the absorption efficiency is 100%. At 10 to 15 ° C, the absorption efficiency is 5% lower. Above
At 33 ° C or below, the absorption efficiency is 10% lower.
10.3 At least two field blanks are to be determined for each batch of samples. Bring the sampling tube with the absorption liquid to the sampling site, except that it does not collect gas.
His environmental conditions are the same as the samples.
10.4 When the concentration of sulfur dioxide in the air is higher than the upper limit of measurement, the sampling volume may be appropriately reduced or the volume of the sample may be reduced.
10.5 If the absorbance of the sample solution exceeds the upper limit of the standard curve, dilute with the reagent blank and measure the absorbance within a few minutes.
However, the di......
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