HJ 742-2015Soil and sediment. Determination of volatile aromatic hydrocarbons. Headspace gas chromatography (English PDF)

6.1 Collection and storage of samples

The collection and storage of soil samples were carried out in accordance with the relevant provisions of HJ/T 166. In accordance with the relevant provisions of GB 17378.3 Collection and storage of sediment samples. Collection of samples of the application of iron shovel and stainless steel spoon. All samples should be collected at least 3 Representative sample.

Use a shovel and a stainless steel spoon to collect the sample as soon as possible into the sampling bottle (5.10) and fill it as much as possible. Quickly remove the sample Bottle threads and samples attached to the outer surface, sealed vials. Placed in a portable freezer and brought back to the laboratory.

The samples in the sampling vials were used for the determination of the dry matter and the moisture content of the sediments.

Note 1. If necessary, the sample can be sieved at the sampling site using a portable instrument for the determination of volatile aromatic hydrocarbons. As if when the volatile aromatic hydrocarbon concentration in the product is greater than 1000 µg/kg, the sample is considered to be a high content sample.

Note 2. Do not stir soil and sediment when collecting samples, so as to avoid the evaporation of organic matter.

3 samples should be analyzed as soon as possible after being sent to the laboratory. If you can not immediately analyze, sealed below 4 °C, the shelf life does not exceed 7d. There should be no organic interference in the sample storage area.

6.2 Preparation of the sample

6.2.1 Low content sample

Take the sample vial (5.10) in the laboratory and wait for 2g (accurate to 0.01g) to be returned to room temperature.

In the bottle, add 10.0 ml of saturated sodium chloride solution (4.5) to the headspace bottle immediately, and immediately seal the reciprocating oscillator (5.4) on the frequency of 150 times/min oscillation 10 min, to be measured.

6.2.2 High content samples

The high content sample is prepared as follows. Remove the sample bottle (5.10) and allow it to return to room temperature. Weigh 2g (accurate to 0.01g) the sample was placed in a headspace bottle and 10.0 ml of methanol (4.2) was added rapidly, sealed on a reciprocating oscillator (5.4) / Min for 10 min. After standing for settling, remove about 1 ml of the extract with a disposable Pasteur glass pipette to 2 ml Brown dense bottle (5.9). The extract can be stored in the freezer at 4 °C, the shelf life of 14 d.

Note 3. If the concentration of the target compound in the methanol extract is high, it can be appropriately diluted by adding methanol.

After recovering the extract to room temperature before analysis, add 2 g (accurate to 0.01 g) quartz sand (4.7) to the empty headspace flask, 10.0 ml of saturated sodium chloride solution (4.5) and 0.010 to 0.100 ml of methanol extract. Immediately sealed in reciprocating oscillator (5.4) on the frequency of 150 times/min oscillation 10 min, to be measured.

Note 4. If the concentration is too low or not detected by high content method, the sample should be re-analyzed using a low content method.

6.3 Preparation of blank samples

6.3.1 Transport blank samples

Before sampling, 10.0 ml of saturated sodium chloride solution (4.5) and 2 g (accurate to 0.01 g) of quartz sand (4.7) Into the top of the bottle sealed, to bring it to the sampling site. Sampling unopened, then shipped back to the laboratory with the sample, in the reciprocating Oscillator (5.4) at 150 times/min oscillation time for 10 min, to be measured.

6.3.2 Low content blank sample

Weigh 2 g (accurate to 0.01 g) quartz sand (4.7) instead of the sample, prepare a low level blank sample according to 6.2.1.

6.3.3 High content blank samples

Weigh 2 g (accurate to 0.01 g) quartz sand (4.7) instead of high content samples, prepare high levels of air according to 6.2.2 White sample.

Determination of Soil Dry Matter Content and Sediment Moisture Content the dry matter content of the soil was determined according to HJ 613; the moisture content of the sediment sample was determined according to GB 17378.5.

7.1 Instrument reference conditions

7.1.1 Headspace sampler reference conditions

Heating equilibrium temperature 85 °C; heating equilibrium time 50 min; sampling needle temperature 100 °C; transmission line temperature 110 °C; transmission Line was subjected to deactivation, the inner diameter of 0.32 mm quartz capillary column; pressure equalization time 1 min; injection time 0.2 min;

Dial time 0.4 min.

47.1.2 Gas chromatograph reference conditions

Temperature programmed. 35 ° C (for 6 min) 5 ° C/min 150 ° C (for 5 min) 20 ° C/min.200 ° C (for 5 min);

Inlet temperature. 220 ° C; detector temperature. 240 ° C; carrier gas. nitrogen; column flow. 1.0 ml/min; hydrogen flow rate. 45 ml/min;

Air flow. 450 ml/min; injection method. split injection; split ratio. 5. 1.

7.2 Calibration curve drawing 25.0 µl, 50 µl, 100 µl, 250 µl, 500 µl of standard stock solution (4.6) were charged with a small amount of methanol in a 5 ml volumetric flask, and then equilibrated with methanol to give a standard solution concentration of 5.00 µg/ml, 10.0 µg/ml, 20.0 Mg/ml, 50.0 µg/ml, 100 µg/ml, and frozen (-18 ° C or lower).

Add 2 g (accurate to 0.01 g) quartz sand (4.7), 10.0 ml saturated sodium chloride solution (4.5) and 10.0 µl of the above standard solution (7.2), the target compound mass was 50.0 ng, 100 ng,.200 ng, 500 ng and a 1000 ng 5-point calibration curve series. According to the instrument reference conditions (7.1) followed by injection analysis to peak area or peak height for the ordinate, the quality (ng) for the abscissa, draw the calibration curve. The standard chromatograms of 12 volatile aromatic hydrocarbons are shown in Fig.

7.5 10.0 12.5 15.0 17.5 20.0 22.5 min 0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 MV (x10,000) 0 2-toluene; 3-ethylbenzene; 4-p-xylene; 5-m-xylene; 6-cumene; 7-o-xylene; 8-chlorobenzene; 3-dichlorobenzene;

-1,4-dichlorobenzene; 12-1,2-dichlorobenzene.

Figure 1 12 kinds of volatile aromatic hydrocarbon standard chromatogram

7.3 Determination

The prepared sample (6.2) was placed on an automatic headspace sampler (5.3) and tested according to instrument reference (7.1) set.

7.4 blank test

Place the prepared blank sample (6.3) on the automatic headspace sampler (5.3) and follow the instrument reference conditions (7.1) Line determination.

Calculation and representation of results

8.1 Qualitative analysis Qualitative analysis was performed based on the retention time of each component of the reference substance.

8.2 Calculation of soil samples

8.2.1 The content of volatile aromatic hydrocarbons in low-content samples (µg/kg) is calculated according to formula (1).

5dmwm

Where. - the content of the target compound in the sample, µg/kg;

M0 - Calculate the mass of the target compound based on the calibration curve, ng;

M1 - sample weight (wet weight), g.

Dmw - dry matter content of the sample,%.

8.2.2 The content of volatile aromatic hydrocarbons in high-content samples (µg/kg) is calculated according to formula (2).

DmS wVm

0 0.10 (2)

Where. - the content of the target compound in the sample, µg/kg;

M0 - according to the calibration curve to calculate the target compound quality, ng;

10.0 - volume of extract, ml;

M1 - sample weight (wet weight), g;

Vs - volume of methanol extract for headspace measurement, ml;

Dmw - dry matter content of sample,%;

F - the dilution factor of the extract.

8.3 Calculation of sediment sample results

8.3.1 Content of volatile aromatic hydrocarbons in low-content samples (µg/kg), calculated according to formula (3).

OHwm

Where. - the content of the target in the sample, µg/kg;

M0 - according to the calibration curve to calculate the target compound quality, ng;

M1 - sample weight (wet weight), g;

OHw 2 - moisture content of the sample,%.

8.3.2 The content of volatile aromatic hydrocarbons in high-content samples (µg/kg) is calculated according to formula (4).

SOH Vwm

0.10

Where. - the content of the target in the sample, µg/kg;

M0 - according to the calibration curve to calculate the target compound quality, ng;

10.0 - volume of extract, ml;

M1 - sample weight (wet weight), g;

Vs - volume of methanol extract for headspace measurement, ml;

OHw 2 - moisture content of the sample,%;

F - the dilution factor of the extract.

8.4 The result is shown when the determination result is less than 100 µg/kg, one decimal place is retained; when the result is greater than or equal to 100 µg/kg,

6 Reserved 3 significant digits.

9 precision and accuracy 9.1 precision Six laboratories tested the soil samples at concentrations of 25.0 µg/kg, 100 µg/kg and 500 µg/kg, respectively the relative standard deviations in the laboratory were 3.3% ~ 17.8%, 0.9% ~ 11.2% and 1.8% ~ 13.0%, respectively.

The relative standard deviations were between 2.4% and 10.1%, 2.1% to 7.8% and 1.3% to 4.8%, respectively.

1.9 µg/kg to 11.9 µg/kg and 30.2 µg/kg to 60.9 µg/kg; reproducibility limits not from 2.0 µg/kg to 3.9 µg/kg, 7.7 µg/kg to 15.0 µg/kg and 30.2 µg/kg to 64.4 µg/kg.

Six samples of the concentration of 25.0 µg/kg, 100 µg/kg, 500 µg/kg of sediment samples were fine the relative standard deviations in the laboratory were 1.7% to 9.2%, 0.9% to 7.3% and 1.2% to 5.2%, respectively.

The relative standard deviations were 1.7% ~ 6.5%, 2.0% ~ 4.4% and 1.3% ~ 2.6%, respectively.

Not to be 1.8 µg/kg to 4.4 µg/kg, 5.6 µg/kg to 10.3 µg/kg and 23.8 µg/kg to 48.5 µg/kg;

Not 2.7 µg/kg to 4.7 µg/kg, 7.1 µg/kg to 14.9 µg/kg and 27.9 µg/kg to 53.1 µg/kg.

9.2 Accuracy

Six laboratories were tested for spiked samples of soil matrix with 25.0 µg/kg, 100 µg/kg and 500 µg/kg the recoveries of the 12 target species were 35.3% ~ 68.7%, 49.3% ~ 90.6% and 37.8% ~ 73.7%.

Six samples of spiked samples with spiked concentrations of 25.0 µg/kg, 100 µg/kg and 500 µg/kg, respectively the determination. The recoveries of 12 kinds of targets were 77.9% ~ 102%, 83.8% ~ 106% and 78.6% ~ 96.5%.

Refer to Appendix B for summary of precision and accuracy.

10 quality assurance and quality control

10.1 Calibration curve According to the concentration of the target and the response value of the calibration curve, the correlation coefficient should be greater than or equal to 0.999, if not satisfied Seek, replace the column or take other measures, and then redraw the calibration curve.

10.2 Calibration Confirmation Before and after each batch analysis, calibration was carried out using the standard curve intermediate concentration point. The target compound was measured the relative deviation between the set value and the standard value should be <= 20%, otherwise the calibration curve should be redrawn.

10.3 samples

10.3.1 Laboratory Blank Test The concentration of all the test compounds in the results of the analysis should be lower than the method detection limit. Otherwise, should Identify the cause, timely elimination, to the laboratory blank test results qualified, to continue the sample analysis.

10.3.2 At least one transport blank sample shall be collected for each batch. The results of the analysis should meet the control index of the blank test (10.3.1), otherwise you need to find the cause, remove the interference after re-acquisition of sample analysis.

10.3.3 Each batch of samples (up to 20) shall be measured with a blank spike, the matrix spike and the matrix the recoveries of the samples were in the range of 80.0% ~ 120%. The recoveries of the spiked samples were in the range of 35.0% ~ 110%, the relative deviation of the matrix calibration results should be less than 20%.

711 Waste treatment

Hazardous wastes containing volatile aromatic hydrocarbons produced in the experiment shall be kept in a centralized manner and entrusted with qualified relevant units for processing.

12 Precautions

12.1 In order to prevent contamination by sampling tools, the sampling tool should be thoroughly washed with methanol and purified water before use. In the collection of its when he samples, pay attention to the replacement of sampling tools and cleaning sampling tools to prevent cross-contamination.

12.2 During sample storage and transportation, to avoid contamination, the sample should be placed in a closed, dark portable refrigerator (5.8) in the cold storage.

12.3 The necessary instruments, materials, medicines, etc. during the analysis shall be analyzed in advance to confirm that they contain interference with the analytical the substance to be measured. Equipment, materials can be washed with methanol, as far as possible in the blank to remove the interference material.

8 Appendix A

(Normative appendix) Method of detection limit, the lower limit of determination when the amount of soil and sediment samples is 2 g, the detection limits of the 12 target species are determined, and the lower limit of determination is shown in Table A.1.

Table A.1 Method Detection limit, lower limit of determination

Compound name English name the detection limit (Mg/kg) Lower limit (Mg/kg) Benzene 3.1 12.4 Toluene 3.2 12.8 Ethylbenzene 4.6 18.4 P-xylene 3.5 14.0 M-xylene 4.4 17.6 Cumene isopropylbenzene 3.4 13.6 O-xylene 4.7 18.8 Chlorobenzene 3.9 15.6 Styrene 3.0 12.0 1,3-dichlorobenzene 3.4 13.6 1,4-dichlorobenzene 4.3 17.2 1,2-dichlorobenzene 3.6 14.4

9 Appendix B

(Informative)

Method of precision and accuracy

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

Table B.1 Method Precision

Compounds

name

Spiked concentration (Mg/kg) Determination of content (Mg/kg) Laboratory relative standard Quasi-deviation (%) Inter-laboratory relative standard deviation(%) Repeatability limit (Mg/kg) Reproducibility limit (Mg/kg) Soil Sediments Soil Sediments Soil Sediments Soil Sediments Soil Sediments Soil Sediments 25.0 25.0 17.2 25.6 3.6 to 4.0 2.0 to 3.0 3.6 3.1 1.9 1.9 2.4 2.8 100 100 90.6 105 0.9 to 3.3 1.7 to 4.0 2.1 3.0 5.9 6.8 7.7 10.8 500 500 369 483 1.8 ~ 3.8 1.2 ~ 2.0 1.3 1.4 30.2 23.8 30.5 29.2 Toluene 25.0 25.0 14.7 23.9 3.9 to 5.7 2.1 to 2...