HJ 1189-2021Water quality Determination of 28 organophosphorus pesticides Gas chromatography-mass spectrometry (English PDF)

6.1 Sample Collection

Sample collection shall be carried out in accordance with the requirements of GB 17378.3, HJ/T 91, HJ 91.1, HJ 164 and HJ 442.3.

After collecting the sample, if the pH value of the water sample is not within the range of 5 to 8, use sulfuric acid solution (4.8) or sodium hydroxide solution (4.11) to collect the water.

Adjust the pH value of the water sample to 5~8 in the device and transfer it to the sample bottle (5.1).

6.2 Storage of samples

After collection, samples should be refrigerated at 4 °C, transported away from light, and analyzed in time. If it cannot be analyzed in time, it should be stored in the refrigerator at 4°C away from light.

The shelf life is 3 days. The extract can be stored frozen at -18 °C with a storage period of 30 d.

6.3 Preparation of samples

6.3.1 Extraction and concentration

6.3.1.1 Surface water, groundwater and seawater

Measure 1 L of water sample into a separatory funnel, add 10.0 µl of the surrogate standard stock solution (4.17), and mix well. Add 30 g chlorine to the water sample Sodium chloride (4.6), shake until completely dissolved, add 25 ml of chloroform (4.1), shake for 2 min, and be careful to release gas. Set aside for stratification, extract Transfer the liquid to a conical flask. The extraction was repeated twice, and the extracts were combined, while retaining the trichlorfon to be tested in the aqueous layer. The extract was purified by anhydrous sodium sulfate (4.7) After dehydration, collect it in a concentration bottle, concentrate it to about 1.0 ml, and then add 3 ml to 5 ml of acetone-n-hexane mixed solution (4.10) to wash the concentrated solution.

shrink the bottle, continue to concentrate until the volume of the extract is less than 0.5 ml, dilute to 1.0 ml with acetone-n-hexane mixed solution (4.10), add 5.0 µl Internal standard stock solution (4.16), to be tested.

Note 1.Sodium chloride may not be added to seawater samples.

Note 2.The temperature during the concentration process cannot be higher than 40 °C.

Note 3.If the concentration of organophosphorus pesticides in the sample exceeds the highest point of the curve, the sampling amount of the sample can be reduced.

6.3.1.2 Domestic and industrial wastewater

Measure 100 ml of the water sample into a separatory funnel, add 10.0 µl of the surrogate standard stock solution (4.17), and mix well. Add 3 g to the water sample Sodium chloride (4.6), shake until completely dissolved, add 10 ml of chloroform (4.1), shake for 2 min, and be careful to release gas. stand for stratification, the extract was transferred to a conical flask. Repeat the extraction twice, and combine the extracts, while retaining the aqueous layer of trichlorfon to be tested. The extract was purified by anhydrous sodium sulfate (4.7) After dehydration, collect it in a concentration bottle, concentrate it to about 1.0 ml, then add 3 ml to 5 ml of acetone-n-hexane mixed solution (4.10) and shake it.

Wash the concentration bottle, continue to concentrate until the volume of the extract is less than 0.5 ml, dilute to 1.0 ml with acetone-n-hexane mixed solution (4.10), add 5.0 µl Internal standard stock solution (4.16), to be tested.

Note. If the concentration of organophosphorus pesticides in the sample exceeds the highest point of the curve, the sampling amount of the sample can be reduced.

6.3.2 Purification and concentration

When the color of the chloroform extract is darker, the extract should be purified.

Use 5 ml of acetone-n-hexane mixed solution (4.10) to activate the graphitized carbon black cartridge (5.6) in advance, and then concentrate the chloroform extract to about 1.0 ml, the extract was added to the activated graphitized carbon black column, followed by 10 ml of acetone-n-hexane mixed solution (4.10) Elution, collect all the eluates, continue to concentrate to about 1.0 ml, then add 3 ml to 5 ml of acetone-n-hexane mixed solution (4.10) and shake Wash the concentration bottle, continue to concentrate until the volume of the extract is less than 0.5 ml, dilute to 1.0 ml with acetone-n-hexane mixed solution (4.10), add 5.0 µl Internal standard stock solution (4.16), to be tested.

6.3.3 Preparation of Trichlorfon Samples

Adjust the pH value of the aqueous phase collected in 6.3.1.1 or 6.3.1.2 to 9-10 with sodium hydroxide solution (4.12), pour it into a conical flask, cover Remove the cap, place it in a water bath at 50 °C for alkaline hydrolysis, and constantly shake the conical flask. After 15 minutes, take out the conical flask, cool it to room temperature, use sulfur After adjusting the pH value of acid solution (4.9) to 5~6, transfer this solution to a separatory funnel, extract and concentrate according to 6.3.1.

6.4 Preparation of blank samples

Replace the water sample with experimental water, and prepare a blank sample according to the same steps as the sample preparation (6.3).

7.1 Instrument reference conditions

7.1.1 Gas chromatography reference conditions

Injection port. temperature 220 °C, splitless; carrier gas. helium; column flow. 1.0 ml/min (constant flow); temperature program. 40 °C (4 min) /min 10°C 270°C (12 min).

7.1.2 Reference conditions for mass spectrometry

Transmission line temperature. 270 °C; ion source temperature. 230 °C; ion source electron energy. 70 eV; data acquisition method. full scan;

Scan quality range. 35 u ~ 500 u.

7.2 Calibration

7.2.1 Instrument performance check

Pipette 1 µl of decafluorotriphenylphosphine (DFTPP) solution (4.19) with a microsyringe and inject it directly into the gas chromatograph (5.2) for separation.

Analysis, the obtained decafluorotriphenylphosphine (DFTPP) key ion abundance should meet the standards specified in Table 1, otherwise it should be mass spectrometer (5.3) parameters to adjust or consider cleaning the ion source.

Note. When using an ion trap or other type of mass spectrometer, the decafluorotriphenylphosphine (DFTPP) key ion abundance standard can be implemented according to the instrument manufacturer's instructions.

9.1 Precision

Six laboratories carried out six repeated determinations of surface water samples spiked with concentrations of 1.0 µg/L, 10.0 µg/L and 90.0 µg/L.

The intra-laboratory relative standard deviations were 6.2%-19%, 4.9%-17% and 3.2%-14%; the inter-laboratory relative standard deviations were 0.6%~4.3%, 1.3%~4.2% and 0.5%~3.7%; the repeatability limits are 0.1 µg/L~0.4 µg/L, 1.6 µg/L~3.5 µg/L and 11 µg/L~27 µg/L; the reproducibility limits are 0.2 µg/L~0.4 µg/L, 1.8 µg/L~3.8 µg/L and 14 µg/L~32 µg/L, respectively.

Six laboratories carried out six repeated determinations of groundwater samples spiked with concentrations of 1.0 µg/L, 10.0 µg/L and 90.0 µg/L.

The intra-laboratory relative standard deviations were 6.1%-19%, 4.9%-17%, and 3.2%-14%; the inter-laboratory relative standard deviations were 0.7%~4.2%, 1.4%~4.5% and 0.5%~4.1%; the repeatability limits are 0.1 µg/L~0.4 µg/L, 1.6 µg/L~3.6 µg/L and 0.1 µg/L~0.4 µg/L, respectively.

11 µg/L~28 µg/L; the reproducibility limits are 0.2 µg/L~0.5 µg/L, 1.8 µg/L~4.2 µg/L and 15 µg/L~36 µg/L, respectively.

Six laboratories carried out six repeated determinations of the domestic sewage with the spiked concentrations of 10 µg/L, 100 µg/L and 900 µg/L respectively.

The intra-laboratory relative standard deviations were 5.2%-14%, 4.4%-10% and 0.5%-8.6%; the inter-laboratory relative standard deviations were 0.5%~2.2%, 0.2%~1.5% and 0.4%~2.6%; repeatability limits are 2 µg/L~3 µg/L, 10 µg/L~24 µg/L and 40 µg/L~ 120 µg/L; the reproducibility limits are 2 µg/L~3 µg/L, 14 µg/L~38 µg/L and 140 µg/L~256 µg/L, respectively.

Six laboratories carried out six repeated determinations of industrial wastewater samples spiked with concentrations of 10 µg/L, 100 µg/L and 900 µg/L.

The intra-laboratory relative standard deviations were 4.3%-14%, 4.0%-10% and 0.5%-9.0%; the inter-laboratory relative standard deviations were 0.5%~2.2%, 0.2%~1.6% and 0.4%~2.5%; the repeatability limits are 2 µg/L~3 µg/L, 10 µg/L~28 µg/L and 51 µg/L~ 141 µg/L; the reproducibility limits were 2 µg/L~3 µg/L, 14 µg/L~33 µg/L and 146 µg/L~225 µg/L, respectively.

In the laboratory, six repeated determinations were carried out on seawater samples with spiked concentrations of 1.0 µg/L, 10.0 µg/L and 90.0 µg/L.

The relative standard deviations within the laboratory were 5.0%-12%, 7.2%-12% and 5.2%-10%, respectively.

For method precision data, see Table C.1 to Table C.4.

9.2 Correctness

Six laboratories carried out six repeated determinations of surface water samples spiked with concentrations of 1.0 µg/L, 10.0 µg/L and 90.0 µg/L.

The recovery rates of standard additions ranged from 36.1% to 99.2%, 52.5% to 100% and 57.2% to 110%, respectively, and the final values of the standard addition recoveries were (37.4 ±2.0)%~(95.5±5.0)%, (54.3±2.9)%~(96.7±5.2)% and (59.1±3.2)%~(106±5.6)%.

Six laboratories carried out six repeated determinations of groundwater samples spiked with concentrations of 1.0 µg/L, 10.0 µg/L and 90.0 µg/L.

The recovery rates of standard additions ranged from 35.1% to 97.2%, 50.9% to 98.3% and 55.5% to 107%, respectively, and the final values of the standard addition recoveries were (36.4 ±2.0)%~(93.5±5.1)%, (52.7±2.8)%~(94.7±5.1)% and (57.5±3.0)%~(103±5.6)%.

Six laboratories carried out six repeated determinations on domestic sewage samples with spiked concentrations of 10 µg/L, 100 µg/L and 900 µg/L.

The recovery rates of standard additions ranged from 43.6% to 98.6%, 59.1% to 108%, and 59.3% to 109%, respectively, and the final values of the standard addition recoveries were (49.5 ±10.7)%~(97.0±2.3)%, (60.0±1.3)%~(107±2.5)% and (60.2±1.3)%~(107±2.5)%.

Six laboratories carried out six repeated determinations of industrial wastewater samples spiked with concentrations of 10 µg/L, 100 µg/L and 900 µg/L.

The recovery rates of standard additions ranged from 45.3% to 93.9%, 60.0% to 107% and 61.1% to 104%, respectively, and the final values of the standard addition recoveries were (51.2 ±10.7)%~(92.4±2.2)%, (60.9±1.3)%~(104±6.5)% and (62.0±1.4)%~(102±2.3)%.

Six replicate determinations were performed in the laboratory on seawater samples spiked at concentrations of 1.0 µg/L, 10.0 µg/L and 90.0 µg/L.

The yields ranged from 37.5% to 98.1%, 43.1% to 99.3% and 59.4% to 107%.

The method accuracy data are shown in Table C.5 to Table C.7.

10.1 Blank test

At least one blank test should be done for every 20 samples or each batch (<=20 samples), and the determination result should be lower than the detection limit of the method.

10.2 Calibration

10.2.1 The relative standard deviation (RSD) of the target relative response factor (RRF) should be <= 20%, or the correlation of the target standard curve Number r>=0.99, otherwise the standard curve should be redrawn;

10.2.2 Every 20 samples or each batch (<=20) samples should be measured at an intermediate check point of the curve, and the measurement result should be consistent with the standard curve.

The relative error of the concentration should be within ±20%, otherwise, a new standard curve should be established.

10.3 Parallel samples

At least one parallel sample should be determined for every 20 samples or each batch (<=20 samples). The relative deviation of the parallel sample determination results should be within ±20% within.

10.4 Matrix spikes

10.4.1 Every 20 samples or each batch (<= 20) samples should be tested for at least one matrix spiked sample, trichlorfon, dichlorvos, the recovery rate of standard addition of phosphorus and systemic phosphorus should be greater than 30%, and the recovery rate of other target compounds should be between 60% and 120%.

Note. Trichlorfon standard stock solution (4.14) and organophosphorus pesticide standard solution (4.15) should be added to the sample at the same time.

10.4.2 The recovery rate of substitutes should be between 60% and 120%.

10.5 Internal Standard

The deviation between the retention time of the internal standard in the sample and the retention time of the internal standard in the calibration of the day or the most recently drawn standard curve should not exceed 0.5 min.

The variation of the quantitative ion peak area should be between 50% and 150%.