Search result: HJ 546-2015 (HJ 546-2009 Older version)
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Ambient air. Determination of phosphorus pentoxide. Molybdenum blue spectrophotometric method
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HJ 546-2015
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| HJ 546-2009 | English | 639 |
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Ambient air. Determination of phosphorus pentoxide. Molybdenum blue ascorbiaccid to deoxidize spectrophotometric method
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HJ 546-2009
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| Standard ID | HJ 546-2015 (HJ546-2015) | | Description (Translated English) | Ambient air. Determination of phosphorus pentoxide. Molybdenum blue spectrophotometric method | | Sector / Industry | Environmental Protection Industry Standard | | Classification of Chinese Standard | Z15 | | Classification of International Standard | 13.040.20 | | Word Count Estimation | 9,945 | | Date of Issue | 2015-12-14 | | Date of Implementation | 2016-02-01 | | Older Standard (superseded by this standard) | HJ 546-2009 | | Quoted Standard | HJ/T 194; HJ/T 374 | | Regulation (derived from) | Ministry of Environment Announcement 2015 No.85 | | Summary | This Standard specifies the determination of phosphorus pentoxide in ambient air - ascorbic acid - molybdenum blue spectrophotometric method. This Standard applies to the determination of ambient air phosphorus pentoxide. When collecting the ambient air is 5.0 m3 (standard state), the sample volume to 50.0ml, detection limit was 0.20��g/m3, measured lower limit of 0.80 ��g/m3. |
HJ 546-2015
Ambient air.Determination of phosphorus pentoxide.Molybdenum blue spectrophotometric method
National Environmental Protection Standard of the People 's Republic of China
Replacing HJ 546-2009
Determination of ambient air phosphorus pentoxide
Molybdenum blue spectrophotometric method
Ambient air-Determination of phosphorus pentoxide-Molybdenum blue
Spectrophotometric method
2015-12-14 release
2016-02-01 Implementation
Ministry of Environmental Protection
Directory
Preface .ii
1 Scope of application .2
2 normative reference documents
3 Principle of the method
4 interference and elimination
5 reagents and materials 2
6 instruments and equipment 3
7 Sample 4
8 Analysis steps
The results are calculated and expressed
10 precision and accuracy
Quality assurance and quality control
12 Waste treatment
Preface
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 Atmospheric Pollution,
Protection of human health, regulate the ambient air phosphorus pentoxide determination method, the development of this standard.
This standard specifies the determination of phosphorus pentoxide in the ambient air by ascorbic acid-molybdenum blue spectrophotometry.
This standard is for the determination of "ambient air phosphorus pentachloride ascorbate reduction - molybdenum blue spectrophotometry (provisional)" (HJ
546-2009).
This standard was first published in.2009, the original standard drafting unit for the Beijing Environmental Protection Monitoring Center. This time for the first time
The main contents of the amendments and amendments are as follows.
- detection limit, interference and elimination of the method, instrumentation, sample collection, sample preparation and analysis steps
To re-provision;
- increased precision and accuracy;
- Added quality assurance and quality control content;
- Increased waste disposal content.
Since the implementation of the standard date, the original standard "Determination of ambient air phosphorus pentaerythritic acid - molybdenum blue light
(Provisional) "(HJ 546-2009).
This standard is organized by the Ministry of Environmental Protection Science and Technology Standards Division.
The main drafting of this standard. Beijing Environmental Protection Monitoring Center
The standard verification unit. Beijing Chaoyang District Environmental Protection Monitoring Station, Beijing Dongcheng District Environmental Protection Monitoring Station, Beijing
Haidian District Environmental Protection Bureau monitoring station, Beijing Environmental Protection Monitoring Center, Sichuan Industrial Environmental Monitoring and Research Institute and Beijing
Measurement North Detection Technology Co., Ltd.
This standard is approved by the Ministry of Environmental Protection on December 14,.2015.
This standard has been implemented since February 1,.2016.
This standard is explained by the Ministry of Environmental Protection.
Ambient air - Determination of phosphorus pentoxide - Molybdenum blue spectrophotometric method
Warning. the use of sulfuric acid in the experiment is corrosive, the operation should be required to wear protective equipment, to avoid contact with the skin
Skin and clothing. Solution preparation and sample pretreatment should be carried out in a fume hood.
1 Scope of application
This standard specifies the determination of phosphorus pentoxide in the ambient air by ascorbic acid-molybdenum blue spectrophotometry.
This standard is applicable to the determination of phosphorus pentoxide in ambient air.
When the ambient air was 5.0 m3 (standard state) and the sample volume was set to 50.0 ml, the detection limit was 0.20 μg/m3,
The lower limit of determination was 0.80 μg/m3.
2 normative reference documents
The contents of this standard refer to the following documents or their terms. Those who do not specify the date of the reference file, the effective version of the appropriate
For this standard.
Technical specification for manual monitoring of ambient air quality
Technical requirements and testing methods for HJ/T 374 total suspended particulate matter sampler
3 Principle of the method
With the vinyl chloride filter to collect particles in the air, particles of phosphorus pentoxide and water to produce orthophosphoric acid. In the acid mediated
In the medium, orthophosphoric acid reacts with ammonium molybdate to produce phosphomolybdic acid in the presence of antimony salts and is immediately reduced by ascorbic acid to form
Blue complex, measured at the wavelength of 700 nm absorbance, phosphorus pentoxide content and absorbance values in line with Lambert - Beer's law.
4 interference and elimination
When the pentavalent arsenic in the sample is greater than 0.02 μg/ml, there is a positive disturbance, adding 2.0 ml of the mixed reducing agent (5.16) at least
Can eliminate 10 μg/ml pentavalent arsenic interference.
5 reagents and materials
Unless otherwise stated, analytical pure chemical reagents are used in accordance with national standards. Experimental water. specific resistance ≥ 18
MΩ · cm.
5.1 sulfuric acid. (H2SO4) = 1.84 g/ml, excellent grade pure.
5.2 Potassium dihydrogen phosphate (KH2PO4). Reference reagent.
5.3 Ammonium molybdate [(NH4) 6Mo7O24 • 4H2O].
5.4 ascorbic acid (C6H8O6).
5.5 Potassium tartrate [K (SbO) C4H4O6 • H2O].
5.6 Sodium sulfite (Na2SO3).
5.7 Sodium thiosulfate (Na2S2O3 • 5H2O).
5.8 Sulfuric acid solution. c (1/2H2SO4) = 5 mol/L.
Measure the amount of 140 ml of sulfuric acid (5.1) and slowly inject it into a beaker containing 500 ml of water while stirring. After cooling, dilute with water
To 1000 ml, mix well.
5.9 Ammonium molybdate solution. [(NH4) 6Mo7O24] = 40 g/L.
Weigh 43.34 g of ammonium molybdate (5.3), dissolved in water and diluted to 1000 ml, mixed, stored in polyethylene plastic bottles,
In 2 ℃ ~ 5 ℃ preservation, preservation period of 1 year.
5.10 Ascorbic acid solution. (C6H8O6) = 17 g/L.
Weigh 2.60 g of ascorbic acid (5.4), dissolved in water and diluted to 150 ml, stored in a brown bottle at 2 ° C to 5 ° C
Save, save period of 7 days, if the color need to re-preparation.
5.11 Antimony potassium tartrate solution. [K (SbO) C4H4O6] = 2.70 g/L.
Weigh 2.74 g of antimony potassium tartrate (5.5), dissolved in water and diluted to 1000 ml, stored in a brown bottle at 2 ° C to 5 ° C
Save, save period of 6 months, if the turbidity need to re-preparation.
5.12 sodium sulfite solution. (Na2SO3) = 100 g/L.
Weigh 100 g sodium sulfite (5.6), dissolve in water and dilute the volume to 1000 ml volumetric flask, mix, store in brown
Color bottle, stored at 2 ~ 5 ℃, storage period of 6 months.
5.13 sodium thiosulfate solution. (Na2S2O3) = 10 g/L.
Weigh 15.70 g sodium thiosulfate (5.7), dissolve in water and dilute to volume to 1000 ml volumetric flask, mix and store
In a brown bottle. Stored at 2 ℃ ~ 5 ℃, the shelf life of 6 months.
5.14 Potassium dihydrogen phosphate standard stock solution. (KH2PO4) = 100 μg/ml.
Accurately weighed 0.1917 g in 105 ℃ ~ 110 ℃ electric oven drying to constant weight of potassium dihydrogen phosphate (5.2), dissolved in water
And diluted volume to 1000 ml volumetric flask, mix, at 2 ℃ ~ 5 ℃ preservation, preservation period of 1 year. This solution is equivalent to every milliliter
Containing 100.0 μg of phosphorus pentoxide.
5.15 potassium dihydrogen phosphate standard use of liquid. (KH2PO4) = 4.0 μg/ml.
Absorb 4.00 ml of potassium dihydrogen phosphate standard stock solution (5.14), diluted with water and volume to 100 ml volumetric flask, temporary use
Now with This solution is equivalent to 4.0 μg of phosphorus pentoxide per milliliter.
5.16 Mixing reducing agent
40 ml of sodium sulfite solution (5.12) and 40 ml of sodium thiosulfate solution (5.13), respectively, were mixed with 20 ml of water
Uniform, with the current allocation.
5.17 Mixing the developer
A mixture of 50 ml of sulfuric acid solution (5.8), 15 ml of ammonium molybdate solution (5.9) and 30 ml of ascorbic acid solution (5.10)
Together, add 5 ml of antimony potassium tartrate solution (5.11), mix well. The color reagent at room temperature can only be stable for 4 h, with the current allocation.
6 instruments and equipment
6.1 Particulate Sampler. In the flow of sampler, sampling head with a filter membrane of the polyethylene mesh pad, the sampling head effective diameter of 80
Mm, can be installed with a diameter of 90 mm filter, sampling flow rate of 80 L/min ~ 130 L/min. Other performance and technical specifications
Shall comply with the requirements of HJ/T 374.
6.2 Visible Spectrophotometer. 3 cm cuvette.
6.3 with a plug color tube. 50 ml.
6.4 Glassware. Unless otherwise noted, the use of A-level glassware in accordance with national standards. Apply hydrochloric acid before use
(1. 5) soaked, no phosphorus detergent and test water followed by cleaning.
6.5 Perchlorethylene filter. 90 mm.
6.6 medium speed quantitative filter paper.
6.7 Common laboratory equipment and equipment.
7 samples
7.1 Collection of samples
The collection of samples shall be carried out in accordance with the relevant requirements of HJ/T 194. The sampler is required to perform flow calibration and gas before each sample
Confidentiality check. The sampling records shall be designed according to the instrument performance and environmental conditions, including the sampling time at the beginning and the end, the flow rate
Or sampling volume, wind direction, wind speed, air temperature, air pressure, humidity, sampling point, sample number and so on. Sampling, the perchlorethylene
The filter (6.5) is packed in the filter holder of the particulate sampler with a sampling flow rate of 100 L/min and a sampling time of 45 min to 60 min.
After sampling, remove the filter with clean tweezers, fold into the clean paper bag or film box back to the laboratory.
7.2 Transport and storage of samples
After collecting the sample filter and the whole program blank filter should be folded into a clean paper bag or film box. If not timely determination,
Should be 2 ℃ ~ 5 ℃ cold storage, dry preservation, within a week.
7.3 Preparation of samples
Take a sample filter, cut into pieces using scissors, placed in a 50 ml beaker, add 10 ml of water to completely wet it,
1.0 ml sulfuric acid solution (5.8), stir and soak for 15 min or more. The solution was filtered to 50 ml with medium speed quantitative filter paper (6.7)
(6.3), and washed with 20 ml of water several beakers and filter residue, washing liquid combined in the colorimetric tube,
To be tested.
7.4 Preparation of blank sample
7.4.1 Full program blank sample
Will be collected with the sample batch of blank filter to the sampling site, do not collect particulate samples, according to the sample transport and
Save (7.2), go back to the laboratory with the sample and prepare the full program blank sample with the preparation procedure (7.3) of the sample.
7.4.2 Laboratory blank samples
A laboratory blank sample was prepared using the two blank filters of the same batch with the sample and the preparation procedure (7.3) of the sample.
8 Analysis steps
8.1 Standard curve
8.1.1 Standard series
Respectively, accurate removal of 0.00 ml, 0.50 ml, 1.00 ml, 3.00 ml, 5.00 ml, 10.00 ml, 15.00 ml dihydrogen phosphate
Potassium standard solution (5.15) was placed in a 50 ml stoppered colorimetric tube (6.3), water was added to a 25 ml scale;
Tube were added 5 ml of water, 1.0 ml of sulfuric acid solution (5.8) and 2.5 ml of mixed reducing agent (5.16), shake, static
Set for 10 min. The concentrations of phosphorus pentoxide in the standard series were 0.00 μg/50 ml, 2.0 μg/50 ml, 4.0 μg/50 ml, 12.0
Μg/50 ml, 20.0 μg/50 ml, 40.0 μg/50 ml, 60.0 μg/50 ml.
8.1.2 color development
In each standard color tube (8.1.1), add 8.0 ml of the mixed developer (5.17), dilute to 50 ml with water
Engraved. Room temperature at 20 ° C above, color 15 min; room temperature at 10 ° C ~ 20 ° C, color 25 min.
8.1.3 colorimetric
At the wavelength of 700 nm, the absorbance was measured with 3 cm cuvette and water as reference. The content of phosphorus pentoxide (μg)
The standard curve is plotted against the absorbance and the regression equation for the standard curve is calculated.
8.2 Determination of sample
Add 2.5 ml of the mixed reducing agent (5.16) to the colorimetric tube of sample (7.3), shake and let stand for 10 min. Press the standard song
(8.1.2 and 8.1.3), the absorbance of the sample (7.3) was measured.
8.3 Determination of blank sample
Add 2.5 ml of the mixed reducing agent (5.16) to the color tube of the blank sample (7.4), shake and let stand for 10 min. Press the standard
(8.1.2 and 8.1.3) at the time of quasi-curve drawing, the absorbance of the whole program blank sample and the laboratory blank sample was measured.
9 Results calculation and representation
9.1 Results calculation
Based on the measured absorbance values, the concentration of phosphorus pentoxide in the sample and the blank sample was calculated from the linear regression equation and
The concentration of phosphorus pentoxide in the ambient air is calculated from the following formula (μg/m3).
NV
OP
Where. 52OP - mass concentration of phosphorus pentoxide in ambient air, μg/m
3;
1 - concentration of phosphorus pentoxide in the sample, μg/50ml;
0 £ - the average of the concentration of phosphorus pentoxide in the laboratory blank sample, μg/50 ml;
50 - sample solution volume, ml;
NV - the sampling volume under the standard state (101.325 kPa, 273 K), m
3.
9.2 The result is shown
When the measured value is greater than or equal to 1.00 μg/m3, the results are expressed as three significant digits; when the measured value is less than 1.00 μg/m3
, The result preserves two decimal places.
10 precision and accuracy
10.1 Precision
Six laboratories were divided into three groups. low, medium and high concentrations (4.0 μg/50 ml, 15.0 μg/50 ml and 40 μg/50 ml)
The standard deviation of the laboratory was 2.9% ~ 6.6%, and the standard deviation of the laboratory was 6%
2.1% ~ 4.7%, 0.5% ~ 3.3%; the relative standard deviation between the laboratory is. 4.9%, 1.2%, 2.5%; repeatability r.
0.48 μg/50 ml, 1.4 μg/50 ml, 2.0 μg/50 ml, reproducibility R were 0.72 μg/50 ml, 1.5 μg/50 ml,
3.3 μg/50 ml.
10.2 Accuracy
6 laboratories were divided into three concentrations [0.180 ± 0.006 mg/L (in terms of phosphorus), 0.500 ± 0.015 mg/L (in terms of phosphorus);
And 1.20 ± 0.07 mg/L (in terms of phosphorus)] were tested in six parallel tests. The relative error scores in the laboratory
Do not be -1.0% ~ 0%, - 0.6% ~ 0.4%, 0% ~ 1.7%; the relative error of the final values were. -0.18% ± 0.009%
-0.07% ± 0.008%, 0.28% ± 0.014%.
(0 ~ 0.5) μg/m3 and (3.0 ~ 4.0) μg/m3, respectively, in the six laboratories were 0.8 μg/m3
And 6.0 μg/m3 of the 6 spike, parallel test, and at the same time to do blank film experiments, the laboratory plus standard recovery were 98% ~
110%, 91% ~ 103%, and the final recoveries were 103% ± 0.08% and 97% ± 0.01%, respectively.
11 quality assurance and quality control
11.1 quality assurance and quality control should be consistent with the requirements of HJ/T 194, sampling and analysis process should avoid touching the membrane with your fingers,
To prevent contamination.
11.2 Each batch of samples should be at least two laboratory blanks and two full program blanks, the determination of the results should be lower than the lower limit of determination.
Otherwise, look for the cause, re-sampling analysis.
11.3 The correlation coefficient of the calibration curve should be greater than or equal to 0.999; each batch of sample should be an intermediate calibration point, the measured value and school
The relative deviation of the corresponding point concentration of the quasi-curve should not exceed 5%, otherwise the calibration curve should be redrawn.
11.4 each batch of samples should be 10% of the proportion of parallel sample determination, the number of samples less than 10, should be measured at least a parallel
The relative deviation of the measured results is not more than 20%.
12 Waste treatment
The waste generated by the experiment should be collected collectively in a covered container and labeled with a label, such as "waste acid", commissioned
Qualified units for processing
......
HJ 546-2009
Ambient air.Determination of phosphorus pentoxide.Molybdenum blue ascorbiaccid to deoxidize spectrophotometric method
National Environmental Protection Standard of the People's Republic
Determination of ambient air phosphorus pentoxide
Ascorbic acid reduction-molybdenum blue spectrophotometry (provisional)
Ambient air-Determination of phosphorus pentoxide
-Molybdenum blue ascorbiaccid to deoxidize spectrophotometric method
Released.2009-12-30
2010-04-01 Implementation
Ministry of Environmental Protection released
Ministry of Environmental Protection
announcement
No. 74 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 lead gas of fixed pollution sources.
The four standards, such as the determination of flame atomic absorption spectrophotometry (tentative), are national environmental protection standards and are released.
The standard name and number are as follows.
I. Determination of lead in fixed pollution sources - Flame atomic absorption spectrophotometry (tentative) (HJ 538-2009);
2. Determination of lead in ambient air by graphite furnace atomic absorption spectrophotometry (tentative) (HJ 539-2009);
III. Determination of arsenic in ambient air and exhaust gases - Spectrophotometric method of silver diethyldithiocarbamate (interim) (HJ 540-2009);
4. Determination of gaseous arsenic in the production of yellow phosphorus - Determination of silver diethyldithiocarbamate spectrophotometry (interim) (HJ 541-2009);
V. Determination of mercury in ambient air - Enrichment of sulfhydryl cotton - Cold atomic fluorescence spectrophotometry (interim) (HJ 542-2009);
6. Determination of mercury in fixed pollution sources - Cold atomic absorption spectrophotometry (provisional) (HJ 543-2009);
VII. Determination of Sulfuric Acid Fog of Fixed Pollution Sources by Ion Chromatography (Provisional) (HJ 544-2009);
VIII. Determination of gaseous total phosphorus in fixed pollution sources - Determination of quinolinol ketone capacity (provisional) (HJ 545-2009);
X. Determination of chlorine gas from fixed pollution sources, iodometric method (provisional) (HJ 547-2009);
XI. Determination of hydrogen chloride in fixed source pollution. Silver nitrate capacity method (provisional) (HJ 548-2009);
12. Determination of hydrogen chloride in ambient air and exhaust gas Ion chromatography (interim) (HJ 549-2009);
XIII. Determination of total cobalt in water quality 5-chloro-2-(pyridylazo)-1,3-diaminobenzene spectrophotometry (provisional) (HJ 550-2009);
14. Determination of Chlorine Dioxide in Water Quality Iodometric Method (Provisional) (HJ 551-2009).
The above standards have been implemented since April 1,.2010 and published by the China Environmental Science Press. The standard content can be found on the website of the Ministry of Environmental Protection.
Special announcement.
December 30,.2009
Content
Foreword..iv
1 Scope..1
2 Normative references..1
3 method principle..1
4 Interference and elimination.1
5 Reagents and materials.1
6 instruments and equipment..2
7 samples. 2
8 Analysis steps..3
9 result calculation..3
10 Quality Assurance and Quality Control.3
Foreword
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 Atmospheric Pollution
This standard is established for the determination of human body health and the regulation of phosphorus pentoxide in the air.
This standard specifies the ascorbic acid reduction-molybdenum blue spectrophotometric method for the determination of phosphorus pentoxide in air.
This standard was formulated by the Science and Technology Standards Department of the Ministry of Environmental Protection.
This standard is mainly drafted by. Beijing Environmental Protection Monitoring Center.
This standard was approved by the Ministry of Environmental Protection on December 30,.2009.
This standard has been implemented since April 1,.2010.
This standard is explained by the Ministry of Environmental Protection.
Iv
Determination of ambient air phosphorus pentoxide
Ascorbic acid reduction-molybdenum blue spectrophotometry (provisional)
1 Scope of application
This standard specifies the ascorbic acid reduction-molybdenum blue spectrophotometric method for the determination of phosphorus pentoxide in air.
This standard applies to the determination of phosphorus pentoxide in air.
The detection limit of this standard is 0.8 μg/50 ml. When the sampling volume is 5 m3, the detection limit is 0.2 μg/m3, and the lower limit of determination is 0.8 μg/m3.
When the sampling volume is 300 L, the detection limit is 0.003 mg/m3 and the lower limit of determination is 0.012 mg/m3.
2 Normative references
The contents of this standard refer to the terms in the following documents. For undated references, the valid version applies to this standard.
HJ/T 194 Technical Specifications for Manual Air Quality Monitoring
GB/T 6682 Analytical laboratory water specifications and test methods
3 Principle of the method
The phosphorus oxide in the air is collected by a filter membrane such as perchloroethylene. After sampling, water and phosphorus pentoxide are added to form orthophosphoric acid. In acidic media
In the presence of bismuth potassium tartrate, orthophosphoric acid reacts with ammonium molybdate to form a phosphorus molybdenum heteropoly acid, which is reduced to a blue complex with ascorbic acid at 700
The absorbance is measured at the nm wavelength to calculate the phosphorus pentoxide content in the air.
4 interference and elimination
When the pentavalent arsenic is greater than 5 μg/ml, the tetravalent silicon is greater than 8 μg/ml, and the hexavalent chromium is greater than 16 μg/ml, there is interference with the determination of this method.
Sodium and sodium thiosulfate solutions eliminate interference.
5 reagents and materials
Unless otherwise stated, analytically pure reagents that meet national standards were used for the analysis. Water, GB/T 6682, third grade.
5.1 Sulfuric acid. ρ (H2SO4) = 1.84 g/ml, excellent grade pure.
5.2 Potassium dihydrogen phosphate. ρ (KH2PO4) = 2.34 g/ml, the reference reagent.
5.3 Sulfuric acid solution. c (1/2H2SO4) = 5 mol/L.
Measure 140 ml of sulfuric acid (5.1), slowly inject into a beaker containing 500 ml of water while stirring, and then dilute to 1000 ml with water after cooling.
Mix well.
5.4 Ammonium molybdate solution. ρ [(NH4)6Mo7O24] = 40 g/L.
Weigh 43.34 g of ammonium molybdate [(NH4)6Mo7O24·4H2O], dissolve in water, dilute to 1 000 ml, mix and store in polyethylene plastic
In the bottle, keep it in the refrigerator.
5.5 Ascorbic acid solution. ρ (C6H8O6) = 17 g/L.
Weigh 2.60 g of ascorbic acid, dissolve in water, dilute to 150 ml, and store in a brown bottle. Store in the refrigerator, if it does not change color
long-term use.
5.6 Potassium bismuth tartrate solution. ρ [K(SbO)C4H4O6]= 2.70 g/L.
Weigh 2.74 g of bismuth potassium tartrate [K(SbO)C4H4O6·1/2H2O], dissolve in an appropriate amount of water, dilute to 1000 ml with water, and mix.
5.7 Sodium sulfite solution. ρ (Na2SO3) = 100 g/L.
Weigh 100 g of sodium sulfite, dissolve in water, transfer to a 1 000 ml volumetric flask, dilute with water to the score line, and mix.
5.8 Sodium thiosulfate solution. ρ (Na2S2O3) = 10 g/L.
Weigh 15.70 g of sodium thiosulfate (Na2S2O3·5H2O), dissolve in water, transfer to a 1 000 ml volumetric flask, and dilute with water to the engraved line.
Mix well.
5.9 Potassium dihydrogen phosphate standard stock solution
Accurately weigh 0.191 7 g of potassium dihydrogen phosphate (5.2) dried in a 105-110 ° C electric oven to a constant weight, dissolved in water, and transferred to 1 000 ml.
In the measuring flask, dilute with water to the scribe line and mix. This solution is equivalent to 100.0 μg of phosphorus pentoxide per ml.
5.10 Potassium dihydrogen phosphate standard use solution
When ready to use, draw 10.00 ml of potassium dihydrogen phosphate standard stock solution (5.9) in a 100 ml volumetric flask, dilute with water to the engraved line, dissolve
The liquid is equivalent to 10.0 μg of phosphorus pentoxide per milliliter. A certified standard solution can also be used.
5.11 Mixed reducing agent
For use, take 40 ml of sodium sulfite solution (5.7) and sodium thiosulfate solution (5.8), and mix well with 20 ml of water.
5.12 Mixed developer
When used, mix 25 ml of sulfuric acid solution (5.3), 7.5 ml of ammonium molybdate solution (5.4) and 15 ml of ascorbic acid solution (5.5).
Together, add 2.5 ml of bismuth potassium tartrate solution (5.6) and mix. The developer was stable for only 4 h at room temperature.
Note 1. Ammonium molybdate and ascorbic acid solution are mixed and added to avoid the formation of silicon molybdenum blue.
Note 2. The addition of bismuth potassium tartrate accelerates the reaction rate at room temperature.
6 instruments
Unless otherwise stated, the analysis uses a Class A glass gauge that complies with national standards.
6.1 Particle sampler. medium flow sampler, 80 ~ 130 L/min; small flow sampler, 10 ~ 15 L/min or 0 ~ 30 L/min.
6.2 Visible spectrophotometer. has a 3 cm cuvette.
6.3 Filter membrane such as perchloroethylene. 0.45 μm.
6.4 Oven.
7 samples
7.1 Sample collection
7.1.1 Sampling with a medium flow sampler
When sampling, install the filter in the filter holder of the particle sampler, sample at a flow rate of 100 L/min for 45 to 60 minutes, and record the sample.
condition. After sampling, the filter is removed with a clean tweezers and placed in the sample box and brought back to the laboratory.
7.1.2 Sampling with a small flow sampler
When sampling, install the filter in the filter holder of the particle sampler, sample at 10 L/min for 10-20 min, and record the sample.
condition. After sampling, the filter is removed with a clean tweezers and placed in the sample box and brought back to the laboratory.
7.2 Preservation of samples
The sample should be stored dry at 0 to 4 ° C and measured within 1 week.
7.3 Preparation of samples
Use a pair of tweezers to remove the sampling filter from the sample box, place it in a 50 ml beaker, add 10 ml of water, and shake the beaker to allow the water to soak the filter.
Add 1.0 ml of sulfuric acid solution (5.3), stir and soak for more than 15 min, and filter the sample in a 50 ml volumetric flask with medium speed quantitative filter paper.
The beaker and the filter residue were washed in portions with 20 ml of water, and the washings were combined in a volumetric flask.
7.4 Preparation of blank samples
Take the same batch of blank filter membrane and follow the steps 7.3 to prepare a blank sample.
8 Analysis steps
8.1 Drawing of standard curves
Take 8 50 ml volumetric flasks and prepare a standard series according to Table 1.
Table 1 Standard series of phosphorus pentoxide
Bottle number 0 1 2 3 4 5 6 7
Potassium dihydrogen phosphate standard use solution (5.10)/ml 0.00 0.10 0.50 0.90 1.30 1.70 2.10 2.50
Phosphorus pentoxide content/μg 0.00 1.00 5.00 9.00 13.0 17.0 21.0 25.0
Add 5 ml of water, 1.0 ml of sulfuric acid solution (5.3) and 2.5 ml of mixed reducing agent (5.11) to the volumetric flask, mix and let stand for 10 min.
Add water to about 40 ml, add 8.0 ml of mixed color developer (5.12), dilute with water to the scribe line, and mix.
The color was developed at room temperature above 20 ° C for 25 min; when the temperature was below 20 ° C, the color was developed for 35 min. 3 cm colorimetric at 700 nm
Dish, using water as a reference, measuring the absorbance, plotting the standard curve of the absorbance with the phosphorus pentoxide content (μg), and calculating the standard curve
Regression equation.
8.2 Determination
Add 2.5 ml of mixed reducing agent (5.11) to the volumetric flask of sample (7.3) and blank sample (7.4), mix and place for 10 min.
The following steps are plotted with the standard curve.
9 Calculation of results
Calculate the mass concentration of phosphorus pentoxide in air according to formula (1).
Nd
(PO)
Mm
ρ −= (1)
Where. ρ (P2O5) - mass concentration of phosphorus pentoxide in air, μg/m3;
M--calculated from the standard curve, the content of phosphorus pentoxide on the sample filter, μg;
M0--calculated from the standard curve, the content of phosphorus pentoxide on the blank filter, μg;
Vnd - the volume of air extracted under standard conditions (101.325 kPa, 273 K), m3.
10 Quality Assurance and Quality Control
Quality assurance and quality control shall be in accordance with HJ/T 194. The sampler should be air tight and flow calibrated before use.
Do not touch the filter membrane with your fingers during the sample and analysis process to prevent contamination.
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