HJ 1225-2021Ambient air-Automatic determination of ozone-Chemiluminescence method (English PDF)

1 Scope of application

This standard specifies a chemiluminescence method for the automatic determination of ozone in ambient air.

This standard applies to the automatic determination of ozone in ambient air.

When the instrument range is 0 nmol/mol ~ 500 nmol/mol, the detection of this method under the reference state (298.15 K, 101.325 kPa) the limit is 4 µg/m3, and the lower limit of determination is 16 µg/m3.

2 Normative references

This standard refers to the following documents or clauses thereof. For dated references, only the dated version applies to this standard.

For undated references, the latest edition (including all amendments) applies to this standard.

HJ 193 Technical specification for installation and acceptance of continuous automatic monitoring system for ambient air gaseous pollutants (SO2, NO2, O3, CO) HJ 654 Technical requirements and detection methods of continuous automatic monitoring system for ambient air gaseous pollutants (SO2, NO2, O3, CO) HJ 818 Ambient air gaseous pollutants (SO2, NO2, O3, CO) continuous automatic monitoring system operation and quality control technical specifications

3 Terms and Definitions

The following terms and definitions apply to this standard.

ozone transfer standard According to relevant operating procedures, it can be accurately reproduced or accurately analyzed, and can be traced to a higher level or higher authoritative standard ozone concentration of transportable equipment. Ozone transfer standards are used to transfer the amount of ozone primary standards or to calibrate ozone analyzers at monitoring sites.

Note. The ozone transfer standard is divided into the generation type ozone transfer standard and the analytical ozone transfer standard according to the working principle. According to the position in the step-by-step transmission of ozone value the position is divided into two-level transfer standard, three-level transfer standard and four-level transfer standard.

productive ozone transfer standard this type of transfer standard only contains an ozone generator and does not contain a UV photometer. The odor that occurs is adjusted by adjusting the power of the generator.

The oxygen concentration cannot be measured in real time for the generated ozone concentration. The Generative Ozone Transfer Standard applies only to the quality of on-site ozone analyzers.

Quantitative control work, not suitable for calibrating analytical ozone transfer standards.

analytical ozone transfer standard this type of delivery standard contains a UV photometer that measures the ozone concentration generated by the ozone generator in real time. Analytical ozone delivery standards can be Used to calibrate analytical ozone transfer standards, generative ozone transfer standards and field ozone analyzers. Some analytical ozone delivery standards come with the ozone generator can measure the ozone concentration while generating ozone, and perform real-time feedback adjustment to the ozone generator.

4 Principles of the method

The sample air enters the instrument reaction chamber through the particulate filter at a constant flow, and the ozone is mixed with the excess nitric oxide for an instant reaction After luminescence, the ozone concentration in the sample air is proportional to the luminescence intensity within a certain concentration range.

5 Interference and cancellation

Particulate matter in the air may accumulate in the sampling line or reaction chamber and interfere with the measurement of ozone.

Install a particulate filter to eliminate the effects of particulate matter.

6 Reagents and Materials

7 Instruments and equipment

8 Analysis steps

9 Result calculation and presentation

10 Accuracy

11 Quality Assurance and Quality Control

11.1 The relevant requirements for the calibration of the ozone analyzer (7.3) shall be implemented in accordance with HJ 818.

11.2 Quantity transfer and quantity traceability of ozone transfer standard (7.4) shall be implemented in accordance with HJ 818.

11.3 The filter membrane holder of the particulate filter should be cleaned at least once every six months; the filter membrane is generally replaced every two weeks.

The frequency of membrane replacement should be increased according to the actual situation.

11.4 The air-tightness of the sampling pipeline should be checked monthly, cleaned every six months, and replaced if necessary.

12 Notes

12.1 When the ozone analyzer (7.3) and the nitrogen dioxide (nitrogen oxide) analyzer are used at the same time, drain the outlet of the ozone analyzer (7.3) Connect a purification tank with oxidant and activated carbon to remove excess nitric oxide and generated nitrogen dioxide in the reaction gas. The purification tank should be replaced regularly Change.

12.2 After replacing the sampling system components or filter membranes, sample air should be collected at a normal flow rate for at least 10 minutes and subjected to saturated adsorption treatment.

The measurement data generated during this period are not considered valid data. This process can also be carried out in the laboratory.