HJ 893-2017Water quality. Determination of volatile petroleum hydrocarbons(C6-C9). Purge and trap/gas chromatography (English PDF)

Foreword

In order to implement the "Law of the People's Republic of China on Environmental Protection" and the "Law of the People's Republic of China on Prevention and Control of Water Pollution", protect the environment, Protection of human health, standardize the determination of volatile petroleum hydrocarbons (C6-C9), the development of this standard.

This standard specifies the purge trap/gas chromatography for the determination of volatile petroleum hydrocarbons (C6-C9) in water.

Appendix A of this standard is an informative annex.

This standard is released for the first time.

This standard by the Environmental Protection Department of Environmental Monitoring Division and Science and Technology Standards Division to develop.

This standard was drafted. Shanghai Environmental Monitoring Center.

This standard verification unit. Jiangsu Provincial Environmental Monitoring Center, Ministry of Industry and Information Technology Institute of the Fifth Electronics, Ningbo City Environment Monitoring Center, Changde Environmental Monitoring Station, Shanghai Chemical Environmental Monitoring Station and Shanghai Qingpu Environmental Monitoring Station.

This standard MEP approved on December 21, 2017.

This standard since February 1, 2018 implementation.

This standard is interpreted by the MEP.

1 Water quality Determination of volatile petroleum hydrocarbons (C6-C9)

Purge trap/gas chromatography Warning. The methanol solvent used in the experiment and the standard samples are toxic and hazardous compounds, the solution should be formulated in the pass Fume hood, the operation should be worn protective equipment, avoid contact with skin and clothing.

1 scope of application this standard specifies the purge trap/gas chromatography for the determination of volatile petroleum hydrocarbons (C6-C9) in water.

This standard applies to surface water, groundwater, seawater, sewage and industrial wastewater volatile petroleum hydrocarbons (C6-C9) the determination.

When the sample volume is 10.0 ml, the detection limit of the volatile petroleum hydrocarbon (C6-C9) method of this standard is 0.02 mg/L, the lower limit of determination is 0.08 mg/L.

When the sample volume is 20.0 ml, the detection limit of the volatile petroleum hydrocarbon (C6-C9) method of this standard is 0.01 mg/L, the lower limit of determination is 0.04 mg/L.

2 Normative references

This standard references the following documents or the terms. For undated references, the effective version applies to this book standard.

GB 17378.3 Marine monitoring code Part 3. Sample collection, storage and transport HJ/T 91 Technical Specifications for Surface Water and Sewerage Monitoring HJ/T 164 Groundwater Environmental Monitoring Technical Specifications

3 Terms and definitions

Volatile petroleum hydrocarbons (C6-C9) volatile petroleum hydrocarbons Under the conditions specified in this standard, the gas chromatogram retention time between 2-methylpentane (including) and n-C10H22 (Not included) between the material.

Note. The definition of volatile petroleum hydrocarbons (C6-C9) include aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic or alkylated aromatic hydrocarbons and so on.

4 Method principle

The target compound in the sample is purged by high-purity nitrogen and adsorbed in a collecting pipe. The collecting pipe is heated and purged with high-purity nitrogen the components which were blown and desorbed were separated by gas chromatography and detected by hydrogen flame ionization detector (FID) Retention time window qualitative, external standard method.

25 Reagents and materials

Unless otherwise specified, the analysis of the use of analytical reagents in line with national standards (experimental water for the newly prepared distilled water or deionized water).

5.1 methanol (CH3OH). excellent grade pure.

5.2 Phosphoric acid. rho (H3PO4) = 1.87 g/ml.

5.3 phosphoric acid solution. 1 9.

5.4 Ascorbic acid (C6H8O6).

5.5 Volatile petroleum hydrocarbon standard stock solution. rho (C6-C9) = 5000 mg/L.

You can buy a certified gasoline standard solution.

5.6 Volatile petroleum hydrocarbon standard solution. rho (C6-C9) = 1250 mg/L.

Add 3.00 ml methanol (5.1) to a 4 ml brown bottle, add 1.00 ml standard stock solution (5.5), and mix well. dense Seal frozen preservation, save for three months.

5.7 Alternative standard solution. rho = 500 mg/L.

Use 4-Bromofluorobenzene (BFB) as an alternative, you can buy a certified standard solution can also be used with high concentrations of standard material system.

5.8 2-methylpentane standard solution. rho (C6H14) = 5000 mg/L.

You can buy a certified standard solution.

5.9 n-Decane standard solution. rho (C10H22) = 5000 mg/L.

You can buy a certified standard solution.

5.10 Nitrogen. Purity 99.999%.

5.11 Hydrogen. Purity 99.99%.

5.12 Air. Decolorized silica gel in addition to water and hydrocarbon pipe to remove the hydrocarbon air, or by 5 E zeolite clean oil-free air.

Note. All of the above organic standard solution, the solvent is methanol. Should be cryopreserved, or according to the certificate to save. Should be returned to room temperature before use, Mix well.

6 instruments and equipment

6.1 Gas Chromatograph. Split/Splitless Inlet, Temperature Programmable, Flame Ionization Detector (FID) Workstations can achieve a certain time range of peak area plus function.

6.2 Purge and Trap. With a 25 ml purge, 100% Tenax adsorbent is used for the trap.

6.3 Column. Quartz capillary column, 30 m × 0.53 mm, thickness 3.0 µm (6% cyanopropyl phenyl - 94% dimethylsiloxane).

6.4 Vials. 40 ml brown glass bottle with silicone rubber - Teflon-lined screw cap.

6.5 Micro syringe. 10 µl, 100 µl, 1000 µl.

6.6 Hermetic syringe. 25 ml (purge trap exclusively for manual injection).

6.7 common laboratory equipment.

37 Samples

7.1 Sample Collection Sample collection according to HJ/T 91, HJ/T 164 and GB 17378.3 of the relevant provisions. Before sampling, you need to join 0.3 g Ascorbic acid (5.4) in the sample vial (6.4); when collecting the sample, allow the water sample to overflow in the vial without air bubbles Add a few drops of phosphoric acid solution (5.3) so that the sample pH <= 2, tighten the cap, labeling. Parallel pairs should be collected for each sample Sample, each batch of samples should be at least one full program blank.

7.2 Sample Storage

The collected samples immediately placed at 4 °C dark storage, within 3 d to complete the analysis. There should be no sample storage area Machine interference.

7.3 full program blank Add 0.3 g of ascorbic acid (5.4) with the same sample vial (6.4) to the sampling site, with the same batch in the field Check the water filled vials, add a few drops of phosphoric acid solution (5.3), so that pH <= 2, tighten the cap, together with the sample back to the real Laboratory.

8 Analysis steps

8.1 Instrument reference conditions 8.1.1 purge and trap reference conditions Purge temperature. 35 °C; Purge time. 11 min; Purge flow rate. 30 ml/min; Desorption time. 0.5 min; Desorption Temperature. 190 °C. Other parameters refer to the instrument manual.

8.1.2 GC reference conditions Inlet temperature..200 °C; Injection mode. splitless injection.

Column temperature. the initial temperature of 38 °C (for 1 min), at a rate of 3.8 °C per minute rose to 80 °C for 1 min, each Min at a rate of 10 ° C to 105 ° C for 5 min and then at a rate of 10 ° C per minute to 150 ° C for 1 min the temperature was raised to 180 ° C at a rate of 10 ° C per minute for 5 minutes. The column flow was nitrogen (5.10). 8.0 ml/min.

Detector. temperature 250 ° C; hydrogen (5.11). 30 ml/min; air (5.12). 300 ml/min.

8.2 Calibration

8.2.1 Determination of retention time window of volatile petroleum hydrocarbon (C6-C9) Pipette 4 µl of 2-methylpentane standard solution (5.8) and n-decane standard solution (5.9) with a micro syringe (6.5) Add to a sample vial (6.4) pre-filled with 40 ml of experimental water, tighten the cap and shake well.

Take 10.0 ml of the standard solution prepared above into the purge tube and keep the time window according to the instrument reference conditions (8.1) determine. The peak start time of volatile petroleum hydrocarbon (C6-C9) was determined from the peak time of 2-methylpentane. The n-decane Peak onset time was determined as the end of volatile petroleum hydrocarbon (C6-C9).

In the standard chromatographic conditions, 2-methylpentane and n-decane standard chromatogram shown in Figure 1.

41-2-methylpentane; 2-n-decane

Figure 1 2-methylpentane and n-decane standard chromatogram

8.2.2 establishment of working curve Use a small amount of syringe (6.5), respectively, remove the appropriate amount of volatile petroleum hydrocarbon (C6-C9) standard solution (5.6) rapid increase Into the corresponding sample bottles with experimental water (6.4), tighten the bottle, shake. Preparation of volatile petroleum hydrocarbons (C6-C9) the concentration series were 0.00 mg/L, 0.06 mg/L, 0.31 mg/L, 1.57 mg/L, 3.13 mg/L and 6.25 mg/L respectively.

Take 10.0 ml of the standard solution prepared above to the purge tube, according to the instrument reference conditions (8.1), from low to high concentration Degree in turn measured. The concentration of abscissa, with a fixed retention time window (8.2.1) within the peak area of all the peak area and is the vertical axis, the establishment of the working curve.

8.2.3 Standard Chart of Volatile Petroleum Hydrocarbons (C6-C9) Under the chromatographic conditions specified in this standard, the standard chromatogram of volatile petroleum hydrocarbons (C6-C9) is shown in Figure 2.

1- volatile petroleum hydrocarbon (2.47 min ~ 17.38 min); 2-4-bromofluorobenzene (16.78 min).

Figure 2 Standard chromatograms of volatile petroleum hydrocarbons (C6-C9)

Note 1. The experimental water preparation of the standard solution is not stable, need to use the current available.

Note 2. Prepare the standard solution with airtight syringes (6.6), respectively, using a small syringe (6.5) to remove a standard amount of standard solution (5.6) and alternative standard solution (5.7) were added directly to airtight syringes (6.6) containing 10.0 ml of experimental water.

8.3 Determination of samples Take 10.0 ml sample and analyze according to the working curve (8.2.2) under the same conditions.

8.4 Blank test

Take 10.0 ml of experimental water, according to the working curve (8.2.2) the same conditions.

Note 1. If using a purge trap with an autosampler, the procedure described above can be performed according to the instrument's instructions.

5 Note 2. It is recommended to add 1 µl of Substitute (5.7) for each sample (including blank samples).

Note 3. The sampling volume can be increased to 20 ml when measuring low concentration samples such as surface water.

9 results calculated and expressed

9.1 Calculation Results the concentration of volatile petroleum hydrocarbon (C6-C9) in the sample is calculated according to equation (1)

a) - (Arho x= (1)

Where. -- concentration of volatile petroleum hydrocarbons (C6-C9) in water samples, mg/L;

A - peak area of the target compound;

a - the intercept of the working curve equation;

b - the slope of the working curve equation;

f - for the dilution factor.

9.2 results indicated when the test result is less than 1 mg/L, keep two digits after the decimal point. When the test result is greater than or equal to 1 mg/L, Keep three significant figures.

10 precision and accuracy

10.1 Precision

Six laboratories respectively contained volatile petroleum hydrocarbons (C6-C9) concentrations of 0.09 mg/L, 1.57 mg/L, and 6.25 mg/L of the blank spiked samples were measured, the relative standard deviation of the laboratory. 1.5% ~ 10.4%; relative standard deviation between laboratories the difference was between 3.9% and 9.4%. The six laboratories separately measured the concentration of volatile petroleum hydrocarbons (C6-C9) of 0.31 mg/L, 1.49 mg/L, 2.79 mg/L of the actual sample spiked determination, the relative standard deviation in the laboratory. 3.5% ~ 14.0%; relative to the laboratory Standard deviation. 6.1% ~ 6.7%. See Appendix A for details.

10.2 Accuracy

Six laboratories separately measured the spiked samples, and the spiked concentrations of volatile petroleum hydrocarbons (C6-C9) were 0.09 mg/L, 1.57 mg/L and 6.25 mg/L, respectively. The spiked recoveries ranged from 82.9% to 120% Groundwater, seawater and waste water samples were spiked, the spiked concentrations of volatile petroleum hydrocarbons (C6-C9) were 0.31 mg/L, 1.57 mg/L, 3.13 mg/L, and the spiked recoveries ranged from 66.8% to 127%.

11 Quality Assurance and Quality Control 11.1 blank determination

11.1.1 Laboratory blank

6 One lab blank should be made for every 20 samples or batches (less than 20 samples). Laboratory blank in the target compound the results of the determination should be below the detection limit of the method.

11.1.2 full program blank the full program blank in the target compound determination results should be below the detection limit.

11.2 Calibration

Calibration curve with a linear fit, the correlation coefficient should be >= 0.999, or need to re-draw the calibration curve. Each batch of points Analyze the midpoint concentration of the calibration curve before sample preparation for routine calibration. The standard solution must be ready for use. Calibration point of the measured value the relative error should be <= 15%.

11.3 Parallel samples at least one parallel sample should be analyzed for every 20 samples or batches (less than 20 samples), parallel sample measurements the relative deviation should be <= 20%.

11.4 Substrate spiking 11.4.1 blank spike at least one blank spiked sample should be analyzed for every 20 samples or batches (less than 20 samples), blanks spiked the recovery of spiked petroleum hydrocarbon should be in the range of 80% ~ 120%.

11.4.2 Sample spiking at least one sample plus standard should be analyzed every 20 samples or batches (less than 20 samples). The actual sample plus standard sample the recovery of volatile petroleum hydrocarbons should be 65% to 130%.

12 Waste treatment

The waste liquid generated in the experiment should be collected intensively and correspondingly identified, commissioned by a qualified unit for processing.

13 Precautions

13.1 During the analysis of this method, if gas leaks in the instrument, blockage of the purging needle and other common problems will affect the score Analyze the accuracy of the results. In order to avoid the above situation affecting the accuracy of the actual sample analysis data, it is suggested to add a substitute for analyzing the sample, the recovery rate of the substitutes is used to trace whether there is any abnormality in the sample analysis process. As in the standard series added a substitute, so play Areas of surrogates should be deducted from the sum of the area of the peak area of the CPP (C6-C9).

13.2 Do not use plastic or rubber materials other than PTFE in the purge and trapping system; the surrounding environment should be clean, to prevent interference with the determination of external pollution.

13.3 Analysis of high concentrations of samples, the need to analyze a blank sample, such as blank samples measured results greater than the detection limit, you must Clean with water, if necessary, 10% aqueous methanol can be used for the entire pipeline cleaning. Until the blank sample measurement results Below the method detection limit.

13.4 All glassware must be thoroughly cleaned and dried in an oven at 130 ° C for 2 h and stored in a clean environment.

7 Appendix A.

(Informative)

The precision and accuracy of the method

Table A.1, Table A.2 gives the precision and accuracy of the method respectively.

Table A.1 method of precision

Compound samples

The average

(mg/L)

Laboratory relative

standard deviation(%) Relative between laboratories standard deviation(%) Repeatability r (mg/L) Reproducibility limit R (mg/L) volatility Petroleum hydrocarbons Blank spiked 0.09 3.9 ~ 10.4 9.4 0.02 0.04 1.54 2.4 ~ 6.4 8.5 0.19 0.41 6.25 1.5 ~ 7.4 3.9 1.02 1.15 Actual sample 0.31 3.5 ~ 14.0 6.7 0.08 0.09 1.49 3.9 ~ 10.0 6.1 0.29 0.37 2.79 3.8 ~ 13.8 6.1 0.57 0.70 4-Bromofluoro Blank spiked 0.05 0.8 ~ 11.7 9.6 0.01 0.02 Groundwater spiked 0.05 1.3 ~ 7.1 3.4 0.01 0.01 Sea water spiked 0.05 1.1 ~ 12.8 6.3 0.01 0.01 Waste water spiked 0.05 1.4 ~ 12.0 7.9 0.01 0.01 2,5-bis Bromoluene Blank spike 0.50 2.2 ~ 19.8 8.7 0.11 0.73 Ground water spiked 0.48 3.5 ~ 14.0 13.9 0.11 0.63 Sea water spiked 0.47 3.9 ~ 10.0 5.0 0.08 0.66 Waste water spiked 0.46 3.8 ~ 13.8 13.3 0.06 0.65

Table A.2 Method Accuracy

Compound samples

Scalar

(mg/L)

Spike recovery

volatility

Petroleum hydrocarbons Blank spiked 0.09 83.0 ~ 119 99.5 8.6 99.5 ± 17.2 1.57 83.4 ~ 120 97.9 8.4 97.9 ± 16.8 6.25 82.9 ~ 120 101 4.7 101 ± 9.4 Surface water spiked 0.31 76.4 ~ 112 94.5 8.9 94.5 ± 17.8 1.57 71.3 ~ 114 94.6 8.8 94.6 ± 17.6 Groundwater spiked 0.31 75.4 ~ 119 96.3 5.9 96.3 ± 11.8 1.57 76.4 ~ 124 95.6 7.1 95.6 ± 14.2

8 Sea water spiked

0.31 85.3 ~ 108 94.9 5.2 94.9 ± 10.4 1.57 73.1 ~ 125 95.4 5.7 95.4 ± 11.4 Waste water spiked 0.31 66.8 ~ 127 93.5 7.6 93.5 ± 15.2 3.13 76.9 ~ 109 86.8 5.3 86.8 ± 10.6 4-Bromofluoro Blank spiked 0.05 80.0 ~ 120 102 8.5 102 ± 17.0 Surface water spiked 0.05 84.0 ~ 124 102 8.1 102 ± 16.2 Groundwater spiked 0.05 82.0 ~ 124 101 8.4 101 ± 16.8 Sea water spiked 0.05 80.0 ~ 130 99.7 10.8 99.7 ± 21.6 Waste water spiked 0.05 74.2 ~ 120 101 10.8 101 ± 21.6 2,5-bis Bromoluene Blank spike 0.50 71.6 ~ 124 101 11.6 101 ± 23.2 Surface water spiked 0.50 64.8 to 140 104 15.1 104 ± 30.2 Groundwater spiked 0.50 75.0 ~ 134 102 10.7 102 ± 21.4 Sea water spiked 0.50 80.8 ~ 132 99.8 10.0 99.8 ± 20.0 Waste water spiked 0.50 79.2 ~ 111 98.7 6.7 98.7 ± 13.4