HJ 698-2014Water quality. Determination of chlorothalonil and deltamethrin. Gas chromatography method (English PDF)

5.4 Concentrated sulfuric acid (H2SO4)

5.5 Anhydrous sodium sulfate (Na2SO4)

After burning at 400 ° C for 4 h, it was cooled and placed in a ground glass bottle and stored in a desiccator.

5.6 Sodium chloride (NaCl)

After burning at 400 ° C for 4 h, it was cooled and placed in a ground glass bottle and stored in a desiccator.

5.7 Sodium sulfate solution. c (Na2SO4) = 1.0 mol/L.

Weigh 142 g of sodium sulfate (5.5) in a small amount of water and dilute to 1000 ml.

5.8 Nitrogen. purity >= 99.999%.

7.1 Acquisition and preservation

Samples were taken with reference to the relevant regulations of HJ/T 91 and HJ/T 164.

Samples were collected using a 500 ml hard ground glass bottle or a brown threaded glass bottle with a Teflon septum.

The sample is stored at 2 ° C ~ 5 ° C, the extraction is completed within 7 days, the extract can be stored for 40 days.

7.2 Preparation of samples

7.2.1 Measure 100.0ml sample into a 250ml separatory funnel, add 10g sodium chloride (5.6), dissolve, add 10ml Hexane (5.1), shaken and vented, placed on a shaker and shaken vigorously for 5 min, allowed to stand for 10 min, layered, and extracted with n-hexane.

The solution was transferred to a 100 ml separatory funnel.

7.2.2 Repeat the extraction once and combine the n-hexane extract.

Note 1. For samples with complex composition, if the emulsification phenomenon is serious during the extraction process, mechanical separation should be used to complete the two-phase separation.

It can be broken by agitation, centrifugation, filtration with glass wool, etc., or it can be broken by freezing.

7.2.3 Purification. Add 5 ml of concentrated sulfuric acid to the extract, vortex the mixture, let stand for 1 minute, and discard the sulfuric acid layer. repeatedly Wash to sulfuric acid layer is colorless, discard the sulfuric acid layer; wash n-hexane with appropriate amount of sodium sulfate solution (5.7), repeat washing to the water phase Neutral, discard the water phase.

Note 2. For cleaner groundwater and surface water samples, the purification step can be omitted.

7.2.4 Dehydrate the n-hexane extract through a drying column (or other type of drying equipment) and wash it with a small amount of n-hexane.

The separatory funnel was 2-3 times, and the washing liquid was dehydrated through a drying column, and all the dehydrated n-hexane was collected and concentrated to a concentration until 5.0ml, to be tested.

7.3 Preparation of blank samples

A sample of 100.0 ml of distilled water was used instead of the sample, and a blank sample was prepared in accordance with the same procedure as in the preparation of the sample (7.2).

8.1 Recommended chromatographic conditions

Inlet temperature. 250 ° C, column flow rate. 1.0 ml/min;

Oven. 30/min 30/min 50 min min 290 min----> ---->°C °C(1).200°C(8) °C(10);

Split injection, split ratio 5.1; injection volume. 1.0 µl.

Detector temperature. 320 °C.

8.2 Drawing a calibration curve

Take 6 10ml volumetric flasks, add appropriate amount of n-hexane (5.1), add 0.0µl, 1.0µl, 2.0µl, 5.0µl, respectively.

10.0 µl, 20.0 µl chlorothalonil standard solution (5.2) and 0.0 µl, 5.0 µl, 10.0 µl, 25.0 µl, 50.0 µl, 100.0 µl cyanide the standard solution of pyrethroid (5.3) was fixed to volume with n-hexane (5.1), and the concentration of chlorothalonil was 0.0 mg/L.

0.010mg/L, 0.020mg/L, 0.050mg/L, 0.100mg/L, 0.200mg/L, the mass concentration of deltamethrin is 0.0 mg/L, 0.050 mg/L, 0.10 mg/L, 0.25 mg/L, 0.50 mg/L, 1.00 mg/L standard series. Standard solution the series concentration (mg/L) is the abscissa, and the corresponding peak response value (peak area or peak height) is plotted on the ordinate.

curve.

8.3 Determination of samples

Use a micro-syringe to take 1.0 µl of the sample to be tested (7.2) into the gas chromatograph, in the same chromatographic strip as the calibration curve.

Determine the retention time and peak area (or peak height) of the chromatographic peak.

8.4 Blank test

While the sample is being analyzed, a blank test should be performed. Take 1.0µl blank sample (7.3) into the gas chromatograph, press

8.3 Determine the same steps for analysis.

9.1 Qualitative analysis

Take a certain amount of chlorothalonil and deltamethrin standard solution, diluted to 20.0µg/L and 100.0µg/L with n-hexane (5.1), Take 1.0 µl of the injection and separate it with column 1 to characterize the retention time of the peaks of chlorothalonil and deltamethrin. Chlorothalonil, the standard chromatogram of deltamethrin is shown in Figure 1.

Figure 1 Standard chromatogram of chlorothalonil and deltamethrin (column 1)

If the target compound is detected, use column 2 to aid in qualitative confirmation, see Figure 2.

Figure 2 Assisted qualitative chromatogram of chlorothalonil and deltamethrin (column 2)

9.2 Quantitative analysis

The concentration (µg/L) of chlorothalonil and deltamethrin in the sample was calculated according to formula (1).

10V

rhorho = × × (1)

In the formula.

rho-- chlorothalonil, deltamethrin mass concentration, µg/L;

1-1-- Calculate the concentration of chlorothalonil and deltamethrin in the sample to be tested according to the calibration curve, mg/L;

V 1--water sample volume, ml;

V2--sample volume, ml.

9.3 Result representation

When the measurement result is less than 1.00 µg/L, it is retained to two decimal places; when the measurement result is greater than or equal to 1.00 µg/L, Keep three significant digits.

10.1 Precision

Six laboratories were tested for uniform samples with chlorothalonil concentrations of 0.500 µg/L, 2.00 µg/L, and 10.0 µg/L, respectively.

The relative standard deviations in the experimental room were. 6.1%~9.0%, 1.2%~7.4%, 1.5%~5.3%;

The deviations were. 5.4%, 4.7%, 2.9%; the repeatability limits were. 0.11µg/L, 0.27µg/L, 1.1µg/L; reproducibility the limits are. 0.12 µg/L, 0.35 µg/L, and 1.3 µg/L.

Uniform samples of deltamethrin concentrations of 2.50 µg/L, 10.0 µg/L, and 50.0 µg/L were tested in 6 laboratories.

The relative standard deviations in the laboratory are. 4.5%~7.8%, 2.6%~6.7%, 3.1%~4.7%;

The standard deviations were. 4.4%, 4.2%, 2.4%; the repeatability limits were. 0.37 µg/L, 1.4 µg/L, 5.6 µg/L; reproducibility the limits are. 0.43 µg/L, 1.8 µg/L, and 6.1 µg/L.

10.2 Accuracy

Six laboratories conducted calibration standards containing chlorothalonil concentrations of 0.500 µg/L, 2.00 µg/L, and 10.0 µg/L.

For the measurement, the relative errors are. -6.2%~0.0%, -5.1%~3.9%, -3.0%~3.0%. Relative error final value it is. -2.7% ± 5.0%, 1.6% ± 7.2%, 0.3% ± 5.2%.

Six laboratories carried out chlorpyrifos addition to the surface water, domestic sewage and industrial wastewater samples, and added the scalar amount.

Do not. 0.050µg, 0.200µg, 1.00µg, the standard addition recovery rate is. the standard recovery is 82.0%~92.0%, 89.0%~95.5%, 89.0%~97.3%, and the final recoveries were 88.0%±8.4%, 92.8%±4.5%, and 93.4%±6.1%.

Six laboratories conducted certified standards for deltamethrin concentrations of 2.50 µg/L, 10.0 µg/L, and 50.0 µg/L, respectively.

For the measurement, the relative errors are. -4.6%~7.2%, -4.8%~3.9%, -4.9%~1.4%, and the relative errors are the final values.

0.2% ± 11%, -1.4% ± 6.8%, -1.9% ± 5.1%.

Six laboratories tested the deltamethrin spikes on surface water, domestic sewage and industrial wastewater samples, and added scalar quantities.

They were. 0.250µg, 1.00µg, 5.00µg, and the recoveries were 92.5%~111%, 90.3%~97.4%, respectively.

93.8%~101%, the final recoveries of the spiked recovery were 101%±17.5%, 94.3%±6.0%, and 97.0%±5.4%, respectively.