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HJ 738-2015Ambient air. Determination of nitroaromatics. Gas chromatography (English PDF)

环境空气硝基苯类化合物的测定气相色谱法

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Issued by

Ministry of Ecology and Environment

Level / Type

National · Mandatory

Issue date

February 7, 2015

Implementation date

April 1, 2015

Scope

HJ 738-2015 is the English-translated version of 环境空气硝基苯类化合物的测定气相色谱法.

HJ 738-2015 — This standard specifies the determination of gaseous nitrobenzene compounds in ambient air by gas chromatography. This standard applies to the determination of nitrobenzene, nitrotoluene and nitrochlorobenzene in ambient air and unorganized emissions.

When the sample volume is 25 L, nitrobenzene, p-nitrotoluene, m-nitrotoluene, o-nitrotoluene, p-nitrochloride the detection limits of benzene, m-nitrochlorobenzene and o-nitrochlorobenzene were 0.001 mg/m3 to 0.002 mg/m3, respectively, and the lower limit of determination was 0.004 Mg/m3 ~ 0.008 mg/m3, see Appendix A.

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Document preview — HJ 738-2015

National Standard of the People's Republic of China

ICS: 13.040.20
Classification: Z 15

Issued by: Ministry of Ecology and Environment

Foreword
1 Scope of application
2 Normative reference documents
3 Principle of the method
4 Reagents and materials
4.5 Standard stock solution. rho = 2.00 mg/ml
4.6 Intermediate solution. rho =.200 mg/L
5 Instruments and equipment
6 Samples
6.1 Collection of samples
6.2 Sample pretreatment
7 Analysis steps
7.1 Chromatographic analysis of the reference conditions
7.2 Calibration
7.3 Sample determination
7.4 Blank test
8.1 Qualitative analysis
8.2 Quantitative analysis
8.3 Results show
9 Precision and accuracy
9.1 Precision
9.2 Accuracy
10 Quality assurance and quality control
10.2 Penetration test
10.3 Blank test
10.4 Continuous calibration
11 Waste treatment

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, Environment, the protection of human health, regulate the ambient air nitrobenzene monitoring methods, the development of this standard.

This standard specifies the gas chromatographic method for the determination of gaseous nitrobenzenes in ambient air and unorganized emissions.

This standard is the first release.

Appendix A of this standard is a normative appendix, Appendix B is an informative appendix.

This standard is organized by the Ministry of Environmental Protection Science and Technology Standards Division.

The main drafting unit of this standard. Tianjin Environmental Monitoring Center.

The standard verification unit. the national environmental protection stench pollution control key laboratory, Tianjin Hexi District environmental monitoring station, Ministry of Agriculture Environmental Protection Research and Testing Institute, Tianjin Tanggu District Environmental Monitoring Station, Tianjin Dongli District Environmental Monitoring Station, Tianjin Dagang District Environmental Monitoring Station.

This standard is approved by the Ministry of Environmental Protection on February 7, 2015.

This standard is implemented as of April 1, 2015.

This standard is explained by the Ministry of Environmental Protection.

Determination of nitrobenzene compounds in ambient air Gas chromatography WARNING. The reagents and standard solutions used in the experiment are volatile, and the process should be carried out in the fume hood.

Line, according to the provisions of the requirements of wearing protective equipment, to avoid contact with the skin.

1 Scope of application

This standard specifies the determination of gaseous nitrobenzene compounds in ambient air by gas chromatography.

This standard applies to the determination of nitrobenzene, nitrotoluene and nitrochlorobenzene in ambient air and unorganized emissions.

2 Normative reference documents

The contents of this standard refer to the terms of the following documents. For those who do not specify a date, the valid version applies to this standard.

Technical Guidelines for Sampling of Semi - Volatile Organic Compounds for Environmental Air Technical specification for manual monitoring of ambient air quality Technical Guidelines for Unorganized Emissions Monitoring of Air Pollutants

3 Principle of the method

The nitrobenzene compounds were collected from the ambient air and the unorganized exhaust gas in a silica gel sampling tube with hexane. acetone (1. 1, V/V) ultrasonic desorption, gas chromatography/electron capture detector (GC/ECD) for separation detection, according to retention time Qualitative and external standard method.

4 Reagents and materials

Unless otherwise stated, analytical pure chemical reagents and distilled water are used in accordance with national standards.

4.1 n-hexane (C6H14). pesticide residues.

4.2 Acetone (C3H6O). pesticide residues.

4.3 Benzene (C6H6). pesticide residues.

4.4 Reference materials. nitrobenzene (C6H5NO2), o-nitrotoluene (C7H7NO2), m-nitrotoluene (C7H7NO2), P-nitrotoluene (C7H7NO2), m-nitrochlorobenzene (C6H4ClNO2), p-nitrochlorobenzene (C6H4ClNO2), o-nitrochlorobenzene (C6H4ClNO2), the purity of the above standard should not be less than 98%, dark storage.

4.5 Standard stock solution. rho = 2.00 mg/ml

2 Weigh 0.05 g (accurate to 0.0001 g) standard (4.4) one by one, move into 25 ml volumetric flask, add 2-3 (4.3) dissolved, and then n-hexane (4.1) constant volume to the mark, shake, transferred into the dense bottle seal, 4 °C closed to avoid Light preservation, period of one year. Can also be purchased directly to prove the standard solution.

4.6 Intermediate solution. rho =.200 mg/L

Nitrobenzene standard stock solution (4.5) in 100 ml brown volumetric flask, with n-hexane. acetone (1. 1, V/V) constant volume, prepared into a mixed standard intermediate liquid, 4 °C conditions can be stored for six months.

4.7 standard working solution.

According to the sensitivity of the gas chromatograph detector, linear requirements and the concentration of nitrobenzene compounds in the sample to be tested, Alkane. acetone (1. 1, V/V) dilute the intermediate solution, prepared into several different concentrations of standard working solution, is now available.

4.8 Silica Sampling Tube. Buy commercially available Silica Sampling Tube, Silicone Sampling Tube Size 20cm long, 6mm OD Diameter 4 mm, the tube is equipped with two 40 mesh silica gel, the former 150 mg, the next paragraph 75 mg, the middle with 2 mm glass wool separated Open, two pieces of silica gel with silanized glass wool plug, filled with both ends of the filling.

4.9 nitrogen. ultra-pure cylinder gas (purity >= 99.999%).

5 Instruments and equipment

5.1 Gas Chromatograph. with capillary column shunt/splitless inlet, with constant current or constant voltage function, programmable temperature, with electricity Sub-capture detectors (ECD) and workstations.

5.2 Atmospheric Sampler. Sampling flow rate can reach 0.1 ~ 1.0 L/min, flow accuracy ± 1%.

5.3 Ultrasonic cleaner. Power 250 W.

5.4 Columns 1. 30 mx0.25 mm, 0.5 m film thickness (crosslinked bonded polyethylene glycol), other equivalent or Tested to verify the capillary column.

5.5 Columns 2.30 mx0.32 mm, 1.0 [mu] m Film thickness (100% dimethylpolysiloxane column), other equivalent or a test-proven capillary column.

5.6 Analysis of the balance. accuracy of 0.0001 g.

5.7 volumetric flask. 100 ml, 25 ml, 10 ml.

5.8 Microinjector. 100 l, 50 l, 10 l.

5.9 General laboratory equipment and equipment commonly used.

6 Samples

6.1 Collection of samples

Refer to HJ/T 55 for distribution, and adjust the flow rate of the atmospheric sampler before sampling (correction method according to HJ/T 194 and HJ 691). Sampling open the silicone sampling tube at both ends of the seal, connected with the sampler immediately after sampling. Mining Sample flow rate of 0.5 L/min, at least 50 min collection of samples. Immediately after sampling, seal the silicone sample tube with a sealing cap, see HJ 3691 on-site sampling, back to the laboratory analysis, at 4 °C, the sample in a closed container with a desiccant can be Save 7 d.

6.2 Sample pretreatment

The silica gel sample tube before and after the silicone were placed in 2 ml vials, add 1.00 ml of n-hexane. acetone (1. 1, V/V), screw cap, room temperature ultrasonic cleaning device in the ultrasonic 20 min (ultrasonic cooling water bath cooling, water temperature can not exceed 35 °C, to prevent solvent evaporation), cooled to room temperature, to be analyzed by gas chromatography.

7 Analysis steps

7.1 Chromatographic analysis of the reference conditions

Inlet temperature. 250 ° C; injection method. split injection, split ratio of 10. 1; oven temperature program. from 90 °C to 10 °C/min heating rate rose to 220 °C and keep 5.0 min; column flow. 2.0 ml/min; injection volume. 1.0 µl; tail blow Gas. nitrogen (4.9); tail blow air flow. 25 ml/min; detector temperature. 250 ° C; carrier gas. nitrogen (4.9).

7.2 Calibration

The operation of the gas chromatograph is carried out according to the instrument instructions. The gas chromatograph is adjusted according to (7.1) instrument operating conditions to the best measurement of the state, the injection analysis, from low to high concentrations of standard working solution (4.7) series, each concentrated Degree of determination 3 times. Record and process data with workstations. The concentration of the corresponding target compound is calculated from the peak area of the corresponding target compound Map, draw the calibration curve.

Reference to the nitrobenzene standard working solution concentration shown in Table 1 below.

Table 1 Reference standard working solution concentration

Compound Name Calibration Solution Concentration (mg/L) Nitrobenzene 0.100 0.200 0.500 1.00 2.00 P-nitrotoluene 0.200 0.400 1.00 2.00 4.00 M-nitrotoluene 0.200 0.400 1.00 2.00 4.00 O-nitrotoluene 0.200 0.400 1.00 2.00 4.00 P-nitrochlorobenzene 0.100 0.200 0.500 1.00 2.00 M-nitrochlorobenzene 0.100 0.200 0.500 1.00 2.00 O-nitrochlorobenzene 0.100 0.200 0.500 1.00 2.00

7.3 Sample determination

The sample (6.2) was measured according to the instrument reference condition (7.1). When the sample concentration exceeded the upper limit of the curve, the samples were diluted and analyzed.

7.4 Blank test

In the analysis of the sample at the same time, each batch of samples should be at least one laboratory blank test to blank silica sample tube instead of the sample the silica gel sampling tube is measured in the same procedure as the actual sample.

Calculation and representation of results

8.1 Qualitative analysis

The qualitative analysis was performed by comparing the retention time of the analyte with the retention time of the reference substance. When the sample matrix is complex, Two different columns with different polarities were used for two-column characterization.

According to the gas chromatographic analysis conditions given in the previous paragraph (7.1), the seven nitrobenzene compounds Reference chromatographic separation diagram, see Figure 1 and Figure 2.

The order of the peaks is 1-nitrobenzene, 2-o-nitrotoluene, 3-m-tolylene, 4-p-nitrotoluene, 5-m-nitrochlorobenzene, base Chlorobenzene, 7-o-nitrochlorobenzene.

Figure 1 Chromatogram of nitrobenzene on column 1

The order of the peaks is 1-nitrobenzene, 2-o-nitrotoluene, 3-m-tolylene, 4-p-nitrotoluene, 5-m-nitrochlorobenzene, base Chlorobenzene, 7-o-nitrochlorobenzene.

Figure 2 Chromatogram of nitrobenzene compounds on column 2

8.2 Quantitative analysis

(Mg/m3), the calculated concentration of the target compound in the sample is calculated according to the formula (1).

Vcf x= i (1)

Where. i - the concentration of component i in the sample, mg/m3;

F - Concentration of nitrobenzene compounds in desorption solution in the pre-silica gel according to the standard curve, mg/L;

CV - sample desorption volume, ml;

5V - Sampling volume of sample (under standard), L.

8.3 Results show

When the determination result is greater than 0.1 mg/m3, the data retains three significant digits; when the determination result is less than 0.1 mg/m3, Reserved to 3 decimal places.

9 Precision and accuracy

9.1 Precision

Six laboratories, respectively, 0.013 mg/m3, 0.080 mg/m3 and 0.400 mg/m3 nitrobenzene compounds air samples Were measured.

The relative standard deviations in the laboratory were 6.0% ~ 13.0%, 2.8% ~ 6.5% and 1.4% ~ 5.1% respectively.

The relative standard deviations were 1.3% ~ 8.7%, 1.5% ~ 5.1% and 1.1% ~ 2.5%, respectively.

The range of reproducibility is 0.0019 ~ 0.0029 mg/m3, 0.0072 ~ 0.040 mg/m3, 0.022 ~ 0.033 mg/m3.

The reproducibility limits range from 0.0019 to 0.0035 mg/m3, 0.0074 to 0.013 mg/m3 and 0.025 to 0.035 mg/m3.

9.2 Accuracy

Six laboratories with standard concentration of 0.010 mg/m3 of ambient air samples and the spiked concentration of 0.40 mg/m3 the results showed that the recoveries were as follows. ambient air 77.5% ~ 88.0%, no Organization emissions of 96.5% to 101%.

Details of precision and accuracy are given in Appendix B.

10 Quality assurance and quality control

Evaluation of desorption efficiency of silica gel sampling tubes the blank silica sampling tube is connected with the sampling pump according to the sampling method, and the quantitative sampling solution is taken with the micro-syringe.

Then insert the silicone sample tube into the air, slowly the standard solution into the silica gel sampling tube, 5 minutes after the pump and the other (6.1) and (6.2). The sample was measured according to the instrument reference conditions (7.1), and the target compound was desorbed Efficiency should be between 90% and 105%.

10.2 Penetration test

If the amount of the object to be measured in the posterior segment of the silica sample tube is greater than or equal to 10% of the amount of the preceding article, indicating a penetration, sampling.

10.3 Blank test

Full program blank and laboratory blank determination results should be less than the method detection limit.

10.4 Continuous calibration

Analysis of each batch of samples, must be used to calibrate the middle of the calibration point for continuous calibration, continuous calibration of the relative error should be less than 20%. When the autosampler is used, continuous calibration is required for every 12 hours; if manual injection is performed, Analysis and intermediate/final analysis steps to be completed within one business day, each batch number of no more than 20.

610.5 parallel sample determination each batch of samples should be 5% parallel to the acquisition of parallel, the relative deviation of the results should be within ± 15%.

Determination of the recoveries of spiked samples each batch of samples should be 5% of the recovery rate, the scene collected parallel to the same sample, the actual sample spiked recovery rate should be 100 ± Less than 30%.

11 Waste treatment

The waste generated in the experiment should be collected collectively and regularly sent to qualified units for processing.

7 Appendix A

(Normative appendix) Method of detection limit and determination of the lower limit

Table A.1 shows the detection limits and the lower limit of the determination of the target compound when the sample volume is 25 L.

Table A.1 Method Detection limits and determination limits

No. Compound Chinese name Compound English name Detection limit mg/m3 Determination of the lower limit mg/m3 1 nitrobenzene Nitrobenzene 0.001 0.004 2-p-nitrotoluene 2-Nitrotoluene 0.002 0.008 3-nitrotoluene 3-Nitrotoluene 0.002 0.008 4-o-nitrotoluene 4-Nitrotoluene 0.002 0.008 5-p-nitrochlorobenzene 1-Chloro-3-nitrobenzene 0.001 0.004 6-nitrochlorobenzene 1-Chloro-4-nitrobenzene 0.001 0.004 7 o-nitrochlorobenzene 1-Chloro-2-nitrobenzene 0.001 0.004

8 Appendix B

(Informative)

Method of precision and accuracy

Table B.1 ~ 2 give the method of repeatability, reproducibility and spike recovery and other precision and accuracy indicators

Table B.1 Precision of the method

The target compound

Precision data summary average value (Mg/m3) Laboratory relative standard Quasi-deviation RSDi (%) Inter-laboratory relative standard Quasi-deviation RSDo (%) Repetitive limit r (Mg/m3) Reproducibility R (Mg/m3) Nitrobenzene 0.008 6.3 1.3 0.0026 0.0024 0.075 1.8 1.6 0.0073 0.0075 0.352 1.1 1.5 0.0225 0.0255 P-nitrotoluene 0.009 8.4 7.1 0.0029 0.0031 0.073 2.1 1.6 0.0083 0.0083 0.369 1.5 1.1 0.0264 0.0264 M-nitrotoluene 0.010 7.9 8.7 0.0027 0.0035 0.073 1.4 1.6 0.0093 0.0091 0.369 1.0 0.2 0.0284 0.0260 O-nitrotoluene 0.009 5.0 3.4 0.0024 0.0023 0.072 3.5 5.1 0.0087 0.0130 0.382 2.4 1.5 0.0310 0.0324 P-nitrochlorobenzene 0.009 8.8 2.6 0.0019 0.0019 0.074 1.8 2.6 0.0400 0.0369 0.387 1.4 2.4 0.0219 0.0324 M-nitrochlorobenzene 0.009 6.3 2.1 0.0024 0.0022 0.074 2.9 3.2 0.0078 0.0098 0.375 1.5 1.8 0.0327 0.0352 O-nitrochlorobenzene 0.010 6.6 2.2 0.0020 0.0019 0.074 2.5 1.5 0.0093 0.0090 0.387 1.9 2.5 0.0222 0.0335

9 Table B.2 Method of accuracy the target compound Accuracy data summary Sample Type Average (mg/m3) Relative error RE (%) Relative error Final RE 2SRE (%) Spike recovery Final value P 3SP (%) Nitrobenzene Ambient air 0.008 20.6 20.6 3.1 79.4 4.5 Exhaust gas 0.393 1.9 1.9 1.8 98.1 2.7 P-nitrotoluene Ambient air 0.008 14.8 14.8 2.2 85.2 3.3 Exhaust gas 0.393 1.9 1.9 0.9 98.1 1.5 M-nitrotoluene Ambient air 0.008 14.9 14.9 2.5 85.1 3.6 Exhaust gas 0.394 1.6 1.6 1.2 98.4 1.8 O-nitrotoluene Ambient air 0.008 15.8 15.8 2.8 84.2 4.2 Exhaust gas 0.394 1.5 1.5 2.5 98.5 3.9 P-nitrochlorobenzene Ambient air 0.009 12.6 12.6 1.5 87.4 2.1 Exhaust gas 0.396 1.1 1.1 0.7 98.9 0.9 M-nitrochlorobenzene Ambient air 0.009 12.9 12.9 1.5 87.1 2.1 Exhaust gas 0.393 1.7 1.7 2.4 98.3 3.6 O-nitrochlorobenzene Ambient air 0.009 12.8 12.8 1.6 87.3 2.4 Exhaust gas 0.394 1.5 1.5 1.1 98.5 1.8

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