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HJ 1004-2018Ambient air - Determination of organic acids (acetate, formate and oxalate) in precipitation - Ion chromatography (English PDF)

环境空气降水中有机酸（乙酸、甲酸和草酸）的测定离子色谱法

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Issued by

Ministry of Ecology and Environment

Level / Type

National · Mandatory

Issue date

December 26, 2018

Implementation date

June 1, 2019

Scope

HJ 1004-2018 is the English-translated version of 环境空气降水中有机酸（乙酸、甲酸和草酸）的测定离子色谱法.

HJ 1004-2018 — This standard specifies ion chromatography for the determination of organic acids (acetic acid, formic acid and oxalic acid) in precipitation. This standard applies to the determination of three organic acids (acetic acid, formic acid and oxalic acid) in precipitation.

When the injection volume is.200 µl, the detection limits of acetic acid, formic acid and oxalic acid are 0.005 mg/L and 0.004 mg/L, respectively. And 0.005 mg/L, the lower limit of determination is 0.020 mg/L, 0.016 mg/L and 0.020 mg/L, respectively.

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Document preview — HJ 1004-2018

National Standard of the People's Republic of China

Classification: Z 15

Issued by: Ministry of Ecology and Environment

Foreword
1 Scope of application
2 Normative references
3 Principle of the method
4 Interference and elimination
5 Reagents and materials
5.11 Mixed standard use solution. rho(C2H4O2)=10.0 mg/L, rho(CH2O2)=5.00 mg/L, rho(H2C2O4)
6 Instruments and equipment
37 Samples
48.4 Blank test

Foreword

To protect the "Environmental Protection Law of the People's Republic of China" and the "Air Pollution Control Law of the People's Republic of China" the environment, to ensure human health, to regulate the determination method of organic acids (acetic acid, formic acid and oxalic acid) in precipitation, and to develop this standard.

This standard specifies ion chromatography for the determination of organic acids (acetic acid, formic acid and oxalic acid) in precipitation.

Appendix A and Appendix B of this standard are informative annexes.

This standard is the first release.

This standard is formulated by the Department of Eco-Environmental Monitoring, the Department of Regulations and Standards of the Ministry of Ecology and Environment.

This standard was drafted. China Environmental Monitoring Station.

This standard is verified by. Liaoning Provincial Environmental Monitoring Experimental Center, Inner Mongolia Autonomous Region Environmental Monitoring Center Station, Taiyuan City Ring Environmental Monitoring Center Station, Yangzhou Environmental Monitoring Center Station, Zhanjiang Environmental Protection Monitoring Station and Environmental Monitoring in Shapingba District, Chongqing station.

This standard is approved by the Ministry of Ecology and Environment on December 26, 2018.

This standard has been implemented since June 1, 2019.

This standard is explained by the Ministry of Ecology and Environment.

1 Determination of organic acids (acetic acid, formic acid and oxalic acid) in ambient air precipitation Ion chromatography Warning. Chemical reagents such as sodium hydroxide used in the experiment are highly corrosive, and formic acid and acetic acid standards have Volatile, reagent preparation process should be carried out in a fume hood; protective equipment should be worn as required to avoid breathing inhalation Road or contact with skin and clothing.

1 Scope of application

This standard specifies ion chromatography for the determination of organic acids (acetic acid, formic acid and oxalic acid) in precipitation.

This standard applies to the determination of three organic acids (acetic acid, formic acid and oxalic acid) in precipitation.

When the injection volume is.200 µl, the detection limits of acetic acid, formic acid and oxalic acid are 0.005 mg/L and 0.004 mg/L, respectively.

And 0.005 mg/L, the lower limit of determination is 0.020 mg/L, 0.016 mg/L and 0.020 mg/L, respectively.

2 Normative references

This standard refers to the following documents or their terms. For undated references, the valid version applies to this standard.

GB 13580.2 Collection and preservation of atmospheric precipitation samples HJ/T 165 acid deposition monitoring technical specification

3 Principle of the method

The target compound in the precipitation sample is separated from the eluent by the eluent, and after being detected by the conductivity detector, Leave time to characterize, peak area or peak height.

4 Interference and elimination

The retention time of fluoride ion and acetic acid is similar, and it is not easy to separate effectively. It is necessary to select an ion chromatography column with strong hydrophilicity of the filler.

And appropriately reduce the eluent concentration.

5 Reagents and materials

Unless otherwise stated, the analysis uses the pure grade reagents that meet the national standards, and the experimental water does not contain the target compound.

And deionized water with a resistivity of >=18.2 Mohm·cm (25°C).

5.1 sodium hydroxide (NaOH).

5.2 Sodium carbonate (Na2CO3).

2 It should be dried at 105 °C ± 5 °C for 2 h before use and stored in a desiccator.

5.3 Sodium bicarbonate (NaHCO3).

Balance in the desiccator for 24 h before use.

5.4 Acetic acid. w (C2H4O2) >= 99.5%.

5.5 Formic acid. w (CH2O2) >= 99.6%.

5.6 anhydrous sodium oxalate. w (Na2C2O4) >= 99.5%, stored in a desiccator.

5.7 Sodium hydroxide solution. rho (NaOH) = 40 g/L.

Weigh 1 g of sodium hydroxide (5.1) and dissolve it to 25 ml with water.

5.8 acetic acid standard stock solution. rho (C2H4O2) = 1000 mg/L.

Accurately remove 0.950 ml of acetic acid (5.4), dissolve in a small amount of water, transfer to a 1000 ml volumetric flask, dilute to volume with water until the mark is transferred to the reagent bottle and refrigerated at 4 ° C or less for two months. A commercially available certified standard solution can also be purchased.

5.9 Formic acid standard stock solution. rho(CH2O2)=1000 mg/L.

Accurately transfer 0.820 ml of formic acid (5.5), dissolve in a small amount of water, transfer to a 1000 ml volumetric flask, dilute to volume with water until the mark is transferred to the reagent bottle and refrigerated at 4 ° C or less for two months. A commercially available certified standard solution can also be purchased.

5.10 Standard stock solution of oxalic acid. rho(H2C2O4)=1000 mg/L.

Accurately weigh 0.4187 g of anhydrous sodium oxalate (5.6), dissolve it in a small amount of water, transfer it to a 250 ml volumetric flask, and dilute with water.

Allow to the mark, transfer to the reagent bottle, refrigerate below 4 °C, can be stored for two months. A commercially available certified standard solution can also be purchased.

5.11 Mixed standard use solution. rho(C2H4O2)=10.0 mg/L, rho(CH2O2)=5.00 mg/L, rho(H2C2O4)

=10.0 mg/L.

Accurately transfer 1.00 ml of acetic acid standard stock solution (5.8), 0.500 ml formic acid standard stock solution (5.9) and 1.00 ml Oxalic acid standard stock solution (5.10) in a 100 ml volumetric flask, dilute to volume with water and transfer to a reagent bottle, 4 ° C Stored in the following refrigerated storage for 7 days.

5.12 Carbonate eluent. c(Na2CO3) = 4.0 mmol/L, c(NaHCO3) = 1.2 mmol/L.

Accurately weigh 0.8480 g of sodium carbonate (5.2) and 0.2016 g of sodium bicarbonate (5.3), dissolve in an appropriate amount of water and transfer to 2000 ml.

Volumetric flask, dilute to volume with water and mix.

Note. The eluent can also be prepared according to the instrument model and column instructions.

5.13 Microporous membrane. 0.45 µm pore size, made of polyethersulfone or hydrophilic polytetrafluoroethylene (hydrophilic PTFE).

6 Instruments and equipment

6.1 Ion Chromatograph. with conductivity detector, suppressor.

6.2 Anion column. 250 mm long, 4 mm inner diameter, polystyrene/divinylbenzene or polyvinyl alcohol.

A functional group such as an alkyl quaternary ammonium or an alkanol quaternary ammonium is bonded to the corresponding anion guard column. Or other equivalent column.

6.3 Vials. Plastic materials such as glass or polyethylene.

6.4 Common instruments and equipment used in general laboratories.

37 Samples

7.1 Sample Collection Sample collection was performed in accordance with the relevant provisions of GB 13580.2 and HJ/T 165. The collected sample was passed through a microporous membrane (5.13) After filtration, transfer to vial (6.3).

7.2 Sample storage

The sample is stored in a refrigerated sealed storage at 4 ° C or less, and measured within 2 days. If the pH is adjusted to 8 to 10 with sodium hydroxide solution (5.7), can be measured within 7 days.

Note. Solid precipitation samples such as snow water should be filtered and sampled after they are naturally melted. Some samples should not be taken for measurement before they are completely melted.

8 Analysis steps

8.1 Instrument Reference Conditions Anion column (6.2), column temperature. 30 ° C. Carbonate eluent (5.12), flow rate. 1.0 ml/min, sample Product..200 µl, cell temperature. 30 °C.

8.2 Establishment of the standard curve Accurately transfer 0 ml, 0.50 ml, 1.00 ml, 5.00 ml, 10.00 ml, 20.00 ml mixed standard solution (5.11) in a set of 100 ml volumetric flasks, dilute to volume with water and mix. The standard series reference mass concentration is shown in Table 1. according to Instrument reference conditions (8.1), measured from low to high concentrations. The mass concentration (mg/L) of the target compound is horizontal the coordinates, peak area or peak height are plotted on the ordinate to establish a standard curve.

Note. The appropriate standard series concentration range can be selected according to the concentration level of the target ion in the sample to be tested.

Table 1 Standard series reference mass concentration

Unit. mg/L

Target compound name 1 2 3 4 5 6 Acetic acid 0 0.050 0.100 0.500 1.00 2.00 Formic acid 0 0.025 0.050 0.250 0.500 1.00 Oxalic acid 0 0.050 0.100 0.500 1.00 2.00

8.3 Sample determination the measurement of the sample was carried out in accordance with the same conditions and procedures as in the establishment of the standard curve (8.2). If the sample concentration is high at the highest point of the standard curve, the sample can also be diluted and measured, and the dilution factor D is recorded.

48.4 Blank test

The sample was replaced with experimental water, and the blank sample was measured in the same conditions and procedures as in the sample measurement (8.3).

9 Calculation and representation of results

9.1 Qualitative analysis Qualitative according to the retention time of the target compound in the sample. Under the reference conditions of this standard, three organic acid mixed standard dissolution the ion chromatogram of the liquid is shown in Figure 1.

Acetic acid

Formic acid

oxalic acid

Figure 1 Ion chromatogram of three organic acids (rho=0.500 mg/L)

9.2 Calculation of results the mass concentration (mg/L) of the target compound (acetic acid, formic acid and oxalic acid) in the sample, calculated according to formula (1) Count.

=rho

Where. rho

- the mass concentration of the i-th organic acid in the sample, mg/L;

- mass concentration of the i-th organic acid obtained from the standard curve, mg/L;

D--Dilution factor of the sample.

9.3 Result representation the retention of the number of digits after the decimal point is consistent with the method detection limit, and up to three significant digits are retained.

Acetic acid

Formic acid

oxalic acid

510 precision and accuracy

10.1 Precision

The concentration of acetic acid and oxalic acid in the six laboratories was 0.020 mg/L, 0.100 mg/L, 1.00 mg/L, and the formic acid concentration was Six replicates of 0.010 mg/L, 0.050 mg/L, and 0.500 mg/L were performed in six replicates. relative in the laboratory the standard deviation is 0.1% to 15%; the relative standard deviation between laboratories is 2.4% to 20%; the repeatability limit is 0.004 mg/L~ 0.089 mg/L; the reproducibility limit is 0.001 mg/L to 0.11 mg/L.

6 laboratories performed 6 replicates on precipitation samples containing acetic acid, formic acid and oxalic acid at a concentration of ND ~ 0.739 mg/L the spiked concentrations of the three organic acids were 0.020 mg/L and 0.200 mg/L. The relative standard deviations in the laboratory were respectively determined.

0.7% to 29%; the relative standard deviation between laboratories is 7.5% to 14%; the repeatability limit is 0.007 mg/L to 0.028 mg/L;

The reproducibility limit is 0.010 mg/L to 0.051 mg/L.

For the specific precision test results, see Table A.1 and Table A.2 in Appendix A.

10.2 Accuracy

Method Accuracy Refer to Table A.3 in Appendix A for specific test results.

11 Quality Assurance and Quality Control

11.1 A blank test should be performed before analyzing the sample. At least 1 should be made for every 20 samples or batches (<=20/batch) Blank sample analysis. The target compound content in the blank sample should be below the method detection limit.

11.2 Establish a standard curve using a standard series of at least 6 concentration points (including zero concentration points). The correlation coefficient of the curve should be >= 0.999. The standard curve should be determined simultaneously for every 20 samples or batches (<= 20 cells/batch).

11.3 At least one parallel sample should be measured for every 20 samples or batches (<=20 cells/batch).

The relative deviation should be <= 30%.

11.4 At least 1 spiked recovery test shall be made for every 20 samples or batches (<=20/batch), and the recovery rate shall be controlled.

The system is between 80% and 120%.

12 Waste treatment

The waste liquid generated in the experiment should be collected centrally, and be identified, classified and managed.

13 Precautions

13.1 If an ion chromatograph with gradient elution conditions is used, a hydroxide eluent system may also be used. Eluent conditions and See Appendix B for chromatograms.

13.2 The high concentration of metal ions in the sample will affect the service life of the column. The ion purification column (Ag/Na column) can be used.

To reduce its impact. The Ag/Na column should be activated according to the instruction manual before use.

6 Appendix A

(informative appendix) Method precision and accuracy the precision and accuracy data for the six laboratory measurements are summarized in Tables A.1, A.2 and A.3.

Table A.1 Precision of the method (blank sample spike)

Target combination

Object name

Standard concentration (mg/L) average value (mg/L) Relative standard in laboratory Quasi-bias (%) Relative standard between laboratories Quasi-bias (%) Repeatability limit r (mg/L) Reproducibility limit R (mg/L) Acetic acid 0.020 0.022 2.4~12 19 0.023 0.051 0.100 0.102 0.7~6.9 15 0.025 0.052 1.00 1.00 0.1 to 4.3 3.2 0.060 0.11 Formic acid 0.010 0.012 4.8~15 20 0.004 0.00 0.050 0.048 1.1 to 3.5 5.9 0.004 0.001 0.500 0.485 0.2~2.6 4.9 0.021 0.076 oxalic acid 0.020 0.022 2.0~11 13 0.089 0.009 0.100 0.096 1.0~5.0 2.4 0.008 0.010 1.00 1.01 0.5 to 1.7 2.8 0.027 0.089

Table A.2 Precision of the method (actual sample spike)

Target combination

Object name

Original concentration (mg/L) Standard concentration (mg/L) Total mean (mg/L) Experimental room relative standard deviation(%) Interlaboratory standard deviation(%) Repeatability limit r (mg/L) Reproducibility limit R(mg/L) Acetic acid ND~ 0.739 0.020 0.021 2.5~13 13 0.007 0.010 0.200 0.206 0.5~9.7 7.8 0.028 0.051 Formic acid ND~ 0.700 0.020 0.020 3.3~21 14 0.008 0.010 0.200 0.190 0.7~8.8 7.5 0.022 0.045 oxalic acid ND~ 0.107 0.020 0.020 3.0~29 12 0.008 0.010 0.200 0.185 0.6~5.2 8.5 0.014 0.046 Note. ND indicates that the measured value of the target compound in the sample is below the method detection limit.

7 Table A.3 Method accuracy (actual sample spike) Target compound name Original concentration (mg/L) spiked concentration (mg/L) Spike recovery (%) Scaling recovery final value ±2 PS (%) Acetic acid ND ~ 0.739 0.020 80.0~119 103±24.4 0.200 89.1~115 102±14.2 Formic acid ND ~ 0.700 0.020 82.7~119 95.9±18.0 0.200 85.9~104 96.0±11.8 Oxalic acid ND~0.107 0.020 86.8~115 101±21.4 0.200 80.2~101 94.4±13.0 Note. ND indicates that the measured value of the target compound in the sample is below the method detection limit.

8 Appendix B

(informative appendix) Reference conditions for the hydroxide eluent system Reference chromatographic conditions. Gradient elution conditions. c (OH-) is 1 mmol/L at 0 min ~ 6 min; 6 min ~ 15 min c(OH-) increased from 1 mmol/L to 8 mmol/L; from 15 min to 45 min, c(OH-) rose from 8 mmol/L to 20 mmol/L; c(OH-) was 1 mmol/L at 45.1 min to 55 min. The eluent flow rate was 1.0 ml/min. Injector Product..200 µl. Column temperature. 30 ° C. Conductivity cell temperature. 30 ° C. The chromatogram is shown in Figure B.1.

Acetic acid

Figure B.1 Ion chromatogram of three organic acids in a hydroxide leaching system (rho=1.00 mg/L)

Acetic acid

Formic acid

oxalic acid

......
This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 8 pages — is available in the English PDF.

Referenced standards

Normative references

GB 13580.2

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