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Ambient air. Dtermination of ozone. Ultraviolet photometric method
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HJ 590-2010
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| Standard ID | HJ 590-2010 (HJ590-2010) | | Description (Translated English) | Ambient air. Dtermination of ozone. Ultraviolet photometric method | | Sector / Industry | Environmental Protection Industry Standard | | Classification of Chinese Standard | Z15 | | Classification of International Standard | 13.040.20 | | Word Count Estimation | 15,128 | | Date of Issue | 2010-10-21 | | Date of Implementation | 2011-01-01 | | Older Standard (superseded by this standard) | GB/T 15438-1995 | | Summary | This standard specifies the determination of ozone in ambient air by UV spectrophotometry. This standard applies to the instantaneous ozone in ambient air measurement, also applies to ozone in ambient air continuous automatic monitoring. This standard applies to the determination of the concentration of ozone in ambient air range is 0. 003 ~ 2mg/m ^ 3. |
HJ 590-2010
Ambient air.Dtermination of ozone.Ultraviolet photometric method
National Environmental Protection Standard of the People's Republic
Replace GB/T 15438-1995
Determination of ambient air ozone by ultraviolet photometry
Ambient air-Determination of ozone
-Ultraviolet photometric method
Released on.2010-10-21
2011-01-01 Implementation
Ministry of Environmental Protection released
Ministry of Environmental Protection
announcement
No. 77 of.2010
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 ambient air ozone.
Six standards, such as the fixed ultraviolet photometry, are national environmental protection standards and are released.
The standard name and number are as follows.
2. Determination of water quality pentachlorophenols by gas chromatography (HJ 591-2010);
3. Determination of water quality nitrobenzene compounds by gas chromatography (HJ 592-2010);
4. Determination of water quality, elemental phosphorus, phosphorus molybdenum blue spectrophotometry (provisional) (HJ 593-2010);
5. Determination of the total amount of water-based developer and its oxides - Iodine-starch spectrophotometry (interim) (HJ 594-2010);
6. Determination of the total amount of water color developing agent 169 Coupler spectrophotometry (provisional) (HJ 595-2010).
The above standards have been implemented since January 1,.2011 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 three national environmental protection standards approved and issued by the former National Environmental Protection Agency shall be abolished.
The name and number are as follows.
1. Determination of ambient air ozone by ultraviolet spectrophotometry (GB/T 15438-1995);
2. Determination of water quality pentachlorophenols by gas chromatography (GB 8972-88);
3. Determination of Total Nitro Compounds in Industrial Wastewater Gas Chromatography (GB 4919-85).
Special announcement.
October 21,.2010
Content
Foreword..iv
1 Scope..1
2 Terms and definitions.1
3 method principle..1
4 interference and elimination. 2
5 reagents and materials. 2
6 instruments and equipment.2
7 Analysis steps..4
8 result calculation..6
9 precision and accuracy..6
10 Quality Assurance and Quality Control.6
Appendix A (Normative) Zero Air Quality Validation and Acceptance Criteria 8
Appendix B (Normative Appendix) Correction of Nitric Oxide in Ambient Air..9
Appendix C (informative) Interference of certain compounds on the UV ozone meter..10
Appendix D (informative) Typical UV Ozone Analyzer Performance Parameters 11
Iv
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 Air Pollution, protect the environment and protect people
This standard is formulated for the health of the body and the monitoring method for the regulation of ozone in the ambient air.
This standard specifies the ultraviolet photometric method for the determination of ozone in ambient air.
This standard is a revision of the "Measurement of Ambient Air Ozone by Ultraviolet Spectrophotometry" (GB/T 15438-1995).
This standard was first published in.1995. The original standard drafting unit was the Anshan Environmental Monitoring Center Station. This is the first revision. Revision
The main contents are.
-- Revised the scope of application of ozone determination in air and its reference conditions.
-- Revised the "Interference and Elimination" clause.
- The physical meaning of the representatives in the formula ln(I/I0) = −aρd is clearly defined. The formula for calculating the ozone concentration has been increased.
-- Added terms and definitions.
-- Added quality assurance and quality control provisions.
-- Supplementary and complete the technical conditions and precautions for testing.
-- Added requirements and confirmation steps for zero air quality.
-- Added Appendix B, Appendix C and Appendix D.
Appendix A and Appendix B of this standard are normative appendices, and Appendix C and Appendix D are informative appendices.
From the date of implementation of this standard, the national environmental protection standard “Environment” approved and issued by the former National Environmental Protection Agency on March 25,.1995
Determination of air ozone by ultraviolet spectrophotometry (GB/T 15438-1995) abolished.
This standard is revised 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 October 21,.2010.
This standard has been implemented since January 1,.2011.
This standard is explained by the Ministry of Environmental Protection.
Determination of ambient air ozone by ultraviolet photometry
WARNING. This method requires the use of toxic gaseous ozone. The ultimate concentration of ozone in the laboratory is.200 μg/m3. Excess ozone
It should be drained into the activated carbon scrubber or outdoors and away from the sampling inlet.
1 Scope of application
This standard specifies the ultraviolet photometric method for the determination of ozone in ambient air.
This standard applies to the instantaneous determination of ozone in ambient air, and also to the continuous automatic monitoring of ozone in ambient air.
This standard applies to the determination of ozone in the ambient air concentration range of 0.003 ~ 2 mg/m3.
2 Terms and definitions
The following terms and definitions apply to this standard.
2.1
Zero air zero air
Refers to air that is free of ozone, nitrogen oxides, hydrocarbons, and any other substances that can cause ultraviolet absorption by the ozone analyzer. Zero space
See Appendix A for methods and acceptance criteria for gas quality.
2.2
Pass standard transfer standard
Refers to the ambient ozone that can be used to calibrate after calibration with an ozone standard reference photometer (SRP) or an ultraviolet calibration photometer (6.2.1).
The analyzer delivers the working standard of accuracy. As a standard for the delivery of ozone, at least standard reference photometer or UV calibration luminosity should be used every 6 months.
Calibrate once.
3 Principle of the method
When the sample air enters the instrument's pneumatic system through the dehumidifier and particulate filter at a constant flow rate, it is divided into two paths, one for the sample.
The air, all the way through the selective ozone scrubber becomes zero air, the sample air and zero air alternately enter the sample absorption under the control of the solenoid valve
The pool (or into the sample absorption and reference cells, respectively), ozone has characteristic absorption of ultraviolet light at a wavelength of 253.7 nm. Set zero air through absorption
The light intensity detected at the time of the pool is I0, and the light intensity detected when the sample air passes through the absorption pool is I, then I/I0 is the light transmittance. Microprocessor of the instrument
According to the Lambert-Beer law formula (1), the ozone concentration is calculated from the light transmittance.
Ln(I/I0) =−aρd (1)
Where. I/I0 - the transmittance of the sample, that is, the ratio of the light intensity of the sample air to zero air;
Ρ--the mass concentration of ozone under the temperature of sampling temperature, μg/m3;
D--the optical path of the absorption cell, m;
A--the absorption coefficient of ozone at 253.7 nm, a=1.44×10−5 m2/μg.
4 interference and elimination
Contaminants with a mass concentration of less than 0.2 mg/m3, which are common in ambient air, do not interfere with the determination of ozone. But when the air is oxidized
When the mass concentrations of nitrogen and sulfur dioxide are 0.94 mg/m3 and 1.3 mg/m3, respectively, the determination of ozone yields approximately 2 μg/m3 and 8 respectively.
Positive interference of μg/m3.
If the particles in the air are not removed, it may accumulate ozone in the sampling line, making the measurement result low, adding particles.
The filter can be removed.
During the residence of the sample air in the sampling line, the nitric oxide and the ozone will react to some extent.
For calibration see Appendix B of this standard.
The interference of other compounds on the UV Ozone Meter is given in Appendix C of this standard.
5 reagents and materials
5.1 sampling pipeline
The sampling line shall be made of an inert material such as glass or polytetrafluoroethylene that does not chemically react with ozone.
Note. In order to shorten the residence time of the sample air in the pipeline, short sampling lines should be used as much as possible. Experiments show that if the sample air stays in the pipeline
Less than 5 s between, the ozone loss is less than 1%.
5.2 particulate filter
The filter is composed of a filter membrane and a support thereof, and the material thereof is an inert material such as polytetrafluoroethylene which does not chemically react with ozone.
Note. 1 The membrane is made of Teflon with a pore size of 5 μm. 2 Generally, the new filter membrane needs to be equilibrated by the ambient air for a period of time to obtain a stable reading.
number. 3 The filter should be replaced periodically according to the concentration of the particles in the environment and the sampling volume. The maximum use time of a piece of filter should not exceed 14 days. When found in 5~
When the ozone content decreases by 5% to 10% within 15 minutes, the filter should be replaced immediately.
5.3 Zero air
Zero air, which meets the requirements of the analytical calibration procedure, can be generated by a zero gas generator or by a zero gas cylinder. If using
In the air, the oxygen content should be 20.9% ± 2% of the synthetic air.
Note. Zero air from different sources may contain different residual materials to produce different UV absorption. Therefore, the zero air supplied to the UV photometer must
The zero air used in the ozone generator is the same source as the calibration ozone concentration.
6 Instruments and equipment
6.1 Environmental Ozone Analyzer
The environmental ozone analyzer is mainly composed of the following parts. A typical UV photometric ozone measurement system is shown in Figure 1.
(1) UV absorption cell
The UV absorption cell should be made of an inert material that does not chemically react with ozone and has good mechanical stability so that optical calibration is not
Affected by changes in ambient temperature. The temperature control accuracy of the absorption cell is ±0.5 °C, and the air pressure control accuracy of the sample in the absorption cell is ±0.2 kPa.
(2) UV light source lamp
For example, a low-pressure mercury lamp emits ultraviolet monochromatic light at 253.7 nm, while 185 nm light (irradiated oxygen produces ozone) through the stone.
British window shielding is removed. The ultraviolet radiation emitted by the light source lamp should be sufficiently stable to meet the analytical requirements (see Appendix D of this standard for parameters).
1. Air input; 2. Particulate filter and dehumidifier; 3. Environmental ozone analyzer; 4. Bypass valve; Scrubber
6. UV light source lamp; 7. Optical lens; 8. UV absorption pool; 9. UV detector; 10. Signal processor
11. Air flow meter; 12. Flow controller; Pump.
Figure 1 Schematic diagram of a typical ultraviolet photometric ozone measurement system
(3) UV detector
It can quantitatively receive 99.5% of the radiation at a wavelength of 253.7 nm. The response of its electronic components and sensors is stable and meets analytical requirements.
(4) Scrubber with bypass valve
Its active component selectively removes ozone from the ambient air sample stream.
(5) Sampling pump
The sampling pump is installed at the end of the gas path (see Figure 1), and the suction air flows through the ozone analyzer to maintain a flow rate of 1 to 2 L/min.
(6) Flow controller
Immediately in front of the sampling pump, the air flow through the ozone analyzer can be properly adjusted.
(7) Air flow meter
Installed behind the UV absorber (see Figure 1), the flow rate ranges from 1 to 2 L/min.
(8) Temperature indicator
It can measure the temperature of the sample air in the UV absorption cell with an accuracy of ±0.5 °C.
(9) Pressure indicator
It can measure the pressure of the sample air in the UV absorption cell with an accuracy of ±0.2 kPa.
6.2 Main equipment for calibration
6.2.1 UV Calibration Photometer
The structure and principle of the UV calibration photometer are similar to those of the environmental ozone analyzer. The accuracy is better than ±0.5%, and the repeatability relative deviation is less than
±1%. But there is no scrubber with built-in ozone removal. Therefore, the zero air supplied to the calibrator must be the same as the zero air of the ozone generator.
source.
Note 1. This instrument is used to calibrate ozone transfer standards or environmental ozone analyzers. Only clean dehumidified filtered calibration gas is allowed. It should not be used.
Determine ambient air. The instrument should be calibrated or calibrated once a year using an ozone standard reference photometer (SRP).
Note 2. Some UV calibration photometers have built-in zero gas source, ozone generator and accurate flow dilution device.
6.2.2 Passing standards
One of the following transfer standards can be selected as the working standard for calibrating an ambient ozone analyzer based on the laboratory conditions.
6.2.2.1 UV Ozone Analyzer
The construction is the same as the environmental ozone analyzer (6.1). However, when used as an ozone transfer standard, it cannot be used to measure ambient air at the same time.
6.2.2.2 Ozone generator with gas distribution device
When connected to a zero gas source, it produces a stable ozone (0.5 μmol/mol or 1.0 μmol/mol) close to the upper limit of the system.
Accurately control the flow of zero air entering the ozone generator, at least 4 levels of dilution of the initial ozone concentration occurring, ozone generated
The concentration is measured using an ultraviolet calibration photometer or an ultraviolet ozone analyzer that has been traced to the previous level. This instrument is used to carry out more on the environmental ozone analyzer
Point calibration and single point calibration.
6.2.3 Output manifold
The material of the output pipeline should be an inert material that does not chemically react with ozone, such as borosilicate glass or polytetrafluoroethylene. To ensure the tube
The pressure inside and outside the line is the same, and the pipeline should have sufficient diameter and exhaust. To prevent backflow of air, the vent should be closed when not in use.
A schematic diagram of a typical UV photometer calibration system is shown in Figure 2.
1. Zero air; 2. Flow controller; 3. Flow meter; 4. Ozone generator; 5. Output manifold; 6. UV calibration photometer interface;
7. Environmental ozone analyzer or other standard interface for transmission; 8. exhaust vent.
Figure 2 Schematic diagram of a typical ozone calibration system gas path
7 Analysis steps
7.1 Calibration of the ozone analyzer
7.1.1 Calibrating the transmission standard with an ultraviolet calibration photometer
7.1.1.1 Calibration of Ozone Generator Type Delivery Standards with UV Calibration Photometer
Connect the zero air, ozone generator and UV calibration photometer according to Figure 2 to adjust the zero air flow into the ozone generator to produce a different
The concentration of ozone is measured by an ultraviolet calibration photometer. The air flow from the input to the output manifold should exceed the total amount required by the instrument.
20%, and properly exceed the atmospheric pressure of the exhaust port.
Operate the instruments in strict accordance with the instrument manual. After the instrument is fully warmed up, run the following calibration steps.
(1) Zero adjustment
Guide zero air into the output manifold until a stable response is obtained (zero air requires a stable output for 15 min). Adjust if necessary
The zero point potentiometer of the ozone generator makes the reading equal to zero or zero compensation. Record the output value (I0) of the UV calibration photometer.
(2) Span adjustment
Adjusting the ozone generator to produce the highest molar fraction of ozone required (0.5 μmol/mol or 1.0 μmol/mol), after stabilization,
Record the output value (I) of the UV calibration photometer. The corresponding ozone concentration is calculated according to formula (2). Adjust the span of the ozone generator if necessary
A potentiometer that causes its indicated output reading to be close to or equal to the calculated concentration value. If span adjustment and zero adjustment are related, they should be repeated
Steps (1) to (2), and then check the zero point and span until no adjustment is made, and the response value of the instrument meets the requirements.
Using the measurement parameters of the UV calibration photometer, output multiples under standard conditions (273.15 K, 101.325 kPa) according to equation (2)
The mass concentration of ozone in the tube.
Ln(/ )101.25 273.15 1
273.15 1.44 10
I IT
Pd
ρ −− = × × ×× (2)
Where. 0ρ - the mass concentration of ozone in the standard state, μg/m3;
D--UV ozone calibration photometer absorption cell optical path, m;
I/I0--the transmittance of ozone-containing air, that is, the ratio of the light intensity of the sample gas to zero air;
1.44×10−5--the absorption coefficient of ozone at 253.7 nm, m2/μg;
P--photometer absorption cell pressure, kPa;
T--photometer absorption cell temperature, °C;
Note. Some UV ozone calibrators directly output the concentration value of ozone, and the above calculation steps can be omitted.
(3) Multi-point calibration
Adjusting the zero air flow into the ozone generator, at least 4 concentration points of ozone occur within the full scale of the instrument (not included)
Zero concentration point and full scale point), the stable output value (ρi) is measured, recorded and calculated for each concentration point.
The output value of the UV calibration photometer is plotted against the dilution ratio of the ozone concentration. Calculate the linearity error of multi-point calibration according to equation (3).
100% ii
RE
ρ ρ−= × (3)
Where. - linearity error at each concentration point, %; iE
0ρ - initial ozone mass concentration or mole fraction, mg/m3 or μmol/mol;
Iρ - the mass concentration or mole fraction of ozone measured after dilution, mg/m3 or μmol/mol;
R--dilution rate, equal to the initial concentration flow divided by the total flow.
Note 1. Repeat this calibration procedure to assess the precision of the calibration.
Note 2. The linearity error of each concentration point must be less than ±3%. Otherwise, check the accuracy of flow dilution.
7.1.1.2 Calibration of Ozone Analyzer Type Delivery Standards with UV Calibration Photometers
Connect the zero air, ozone generator, UV calibration photometer and UV ozone analyzer according to Figure 2, in the same steps as in 7.1.1.1.
Zero adjustment, span adjustment and multi-point calibration, and record and calculate the output value of the UV calibration photometer and the response of the ozone analyzer
value. The calibration curve is drawn by the measured value of the ultraviolet calibration photometer corresponding to the response value of the ozone analyzer. The slope of the calibration curve should be 0.97~
Between 1.03, the intercept should be less than ±1% of full scale, and the correlation coefficient should be greater than 0.999.
7.1.2 Calibrating the Environmental Ozone Analyzer with Transfer Standards
Connect the zero air, ozone generator, environmental ozone analyzer and the UV ozone analyzer passed through the previous level according to Figure 2 or other transmission
Standard, according to the same steps as 7.1.1.1, perform zero adjustment, span adjustment and multi-point calibration, and record the environmental ozone analyzer separately.
output value. A calibration curve is drawn by passing the standard reference value corresponding to the response of the ozone analyzer. The slope of the calibration curve should be between 0.95 and 1.05
The intercept should be less than ±1% of full scale and the correlation coefficient should be greater than 0.999.
7.2 Determination of ozone in ambient air
Install an ozone analyzer in a temperature-controlled laboratory to reduce the effects of any temperature changes on the instrument; according to the manufacturer's operation
Correctly set various parameters, including the sensitivity of the UV light source lamp, sampling flow rate; activate the electronic temperature and pressure compensation function;
Introduce zero air and sample gas, check the zero point and span, and record the ozone concentration with a suitable recording device.
8 Calculation of results
Most ozone analyzers measure the temperature and pressure of the sample air in the absorption cell and automatically sample the state based on the measured data.
The mass concentration of ozone is converted to the mass concentration under standard conditions. Otherwise, it must be calculated according to formula (4).
101.325 273.15
273.15
ρ ρ = × × (4)
Where. 0ρ - mass concentration of ozone in standard state, mg/m3; ρ - instrument reading, sampling temperature, mass concentration of ozone under pressure, mg/m3;
P--photometer absorption cell pressure, kPa;
T--photometer absorption cell temperature, °C;
9 Precision and accuracy
9.1 precision
When the confidence level is 95%, the repeatability of the method is within ±5%.
Note. The repeatability of ozone in ambient air is determined to be within ±3.5% (including calibration analysis and reproducibility of environmental analysis).
9.2 Accuracy
The accuracy of the method is better than ±4% of the measured mass concentration.
10 Quality Assurance and Quality Control
10.1 Requirements for calibration
10.1.1 Zero and span check
The ambient ozone analyzer should check the zero point, span and operating parameters before each run. Every two weeks during the continuous operation of the instrument
Check zero and span (or 80% full scale). Zero drift should not exceed 2%, span drift should not exceed ±15% of full scale, no
Then, adjust the analyzer to perform multi-point calibration.
10.1.2 Passing standard calibration
The transfer standard used to calibrate the ambient ozone analyzer is calibrated at least once every 6 months with an ultraviolet calibration photometer at each mass concentration point.
The linearity error must be less than ±3%. Otherwise, check the accuracy of the flow dilution or recalibrate.
10.1.3 Multi-point calibration
The ambient ozone analyzer should run a multi-point calibration every 6 months. The linearity error of each mass concentration point should be less than ±5%, correlation coefficient
Should be greater than 0.999, the intercept should be less than ±1% of full scale. Otherwise, check the accuracy of the flow dilution or calibrate the instrument.
10.1.4 Calibration of UV Calibration Photometer
Calibrate at least once a year with an ozone standard reference photometer (SRP). The linearity error of each mass concentration point should be less than ±1%, and the intercept should be
Less than 3 nmol/mol. Otherwise, check the accuracy of the flow dilution or repair the instrument.
10.2 Replacing the scrubber
Replace the scrubber of the zero gas generator every 6 months. After replacing the scrubber, you should run a multi-point calibration.
10.3 Flow Calibration
10.3.1 The flow control device of the environmental ozone analyzer shall use the working standard at least every six months (refer to the mass flow transmitted by the relevant state departments).
The meter and the electronic soap membrane flow meter are calibrated once, and the flow accuracy should be ±10% of the nominal flow rate.
10.3.2 Flow control device used as an ozone transfer standard (ozone generator with gas distribution device), at least annually sent to a qualified department
Line quality inspection and standard transfer 1 time, the flow accuracy should be ± 1% of the nominal flow.
Appendix A
(normative appendix)
Zero air quality confirmation and acceptance criteria
A.1 Confirmation of zero air quality
A.1.1 Equipment
1 bottle of ultra-high purity zero gas (cylinder); ......
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