HJ 1071-2019Water quality--Determination of glyphosate--High performance liquid chromatography (English PDF)

7.1 Sample collection and storage

Collect the samples in accordance with the relevant regulations of HJ 91.1, HJ/T 91 and HJ/T 164.

Collect the sample with a brown sampling bottle (6.7) and collect the sample in a full bottle. If the pH of the collected sample is not between 4-9, use Adjust the pH to 4-9 with hydrochloric acid solution (5.7) or sodium hydroxide solution (5.8). Keep refrigerated and protected from light below 4 °C, within 7 days Complete sample analysis.

7.2 Preparation of test specimens

7.2.1 Purification by solid phase extraction

Activate the solid phase extraction column (6.3) with 6 ml of methanol (5.2) and 6 ml of water in order to ensure that the column head is infiltrated. measure for a 10 ml sample, add 29.3 mg of trisodium citrate dihydrate (5.10) and mix well at about 3 ml/min (about 1 drop/second).

The flow rate was passed through a solid-phase extraction column, and the purified sample was collected and derivatized.

Note 1. For samples with good cleanliness and no obvious interference to the determination of target compounds, trisodium citrate dihydrate can be added (5.10) After filtering directly through the filter membrane (5.18), it will be derived.

Note 2. If the sample concentration is high, first dilute the sample, add trisodium citrate dihydrate (5.10), and then perform solid phase extraction purification, wait for the Raw.

7.2.2 Derivatization reaction

Take 2.00 ml of the purified sample into a polyethylene plastic (PE) tube (6.4) and add 0.50 ml of sodium tetraborate solution (5.12), 1.00 ml of 9-fluorenyl methyl chloroformate acetonitrile solution (5.14), mix thoroughly and place on a horizontal shaker (6.5) Derived at 40 ° C for 1 h.

7.2.3 Liquid-liquid extraction purification

Add 5 ml of dichloromethane (5.3) to the derivatized sample and vortex on a vortex shaker (6.6) for 2 min.

Take the aqueous layer and filter it through a filter membrane (5.18). Collect 1 ml of the filtrate in a brown sample bottle (6.8) for testing.

7.3 Preparation of blank samples

Use experimental water to replace the sample, and follow the same steps as the sample preparation (7.2) to prepare a laboratory blank sample.

8.1 Reference conditions for liquid chromatography

Mobile phase A. acetonitrile (5.1), mobile phase B. phosphoric acid solution (5.9), the gradient elution procedure is shown in Table 1;

Flow rate. 1.0 ml/min; column temperature. 30 ° C; injection volume. 20 µl;

Excitation wavelength. 254 nm;

Emission wavelength. 302 nm as the detection wavelength and 315 nm as the auxiliary qualitative wavelength.

Table 1 Gradient elution procedure

Time (min) Mobile phase A (%) Mobile phase B (%) Note. 15 minutes to 20 minutes are used to clean the column. The cleaning time can be adjusted according to the complexity of the actual sample. 20 min ~ 25 min is the equilibration time of the column.

8.2 Establishment of working curve

Take an appropriate amount of glyphosate standard use solution (5.17) and dilute with water to prepare a standard series of at least 5 concentration points, the mass concentration of glyphosate is 0 µg/L, 10 µg/L, 20 µg/L, 50 µg/L, 100 µg/L,.200 µg/L, 500 µg/L (This is the reference concentration).

Perform derivatization reaction according to step 7.2.2, liquid-liquid extraction and purification according to step 7.2.3, and then according to the instrument reference conditions (8.1) Inject the standard series solution from low concentration to high concentration, take the concentration of glyphosate as the abscissa, and the corresponding chromatographic peak area or the peak height is the ordinate to establish a working curve.

8.3 Sample determination

The measurement of the sample (7.2) is carried out according to the same instrument conditions as the establishment of the working curve (8.2).

8.4 Blank test

The blank sample (7.3) was measured under the same instrument conditions as the sample measurement (8.3).

9.1 Qualitative analysis

Qualitative according to the retention time of the target compound in the sample, if necessary, standard addition method, fluorescence at different wavelengths can be used Intensity ratio and other methods assist qualitative analysis.

Under the reference conditions of liquid chromatography recommended in this standard (8.1), the standard color of the derivative corresponding to the 100 g/L glyphosate solution the spectrum is shown in Figure 1.

Figure 1 Standard chromatogram of glyphosate derivative

9.2 Quantitative analysis

The glyphosate in the sample was quantified by external standard method, and the mass concentration of glyphosate was calculated according to formula (1).

rho = rho

In the formula. rho-mass concentration of glyphosate in the sample, µg/L;

rho1--the concentration of glyphosate calculated from the working curve, µg/L;

D--The dilution factor of the sample.

9.3 Representation of results

The number of digits after the decimal point in the measurement result is the same as the detection limit of the method. A maximum of 3 significant digits are retained.

10.1 Precision

Six laboratories performed six replicate determinations of surface water samples with glyphosate spiked concentrations of 10 µg/L and 100 µg/L.

The relative standard deviations in the laboratory are 2.2% ~ 9.2%, 2.5% ~ 8.5%, and the relative standard deviations between laboratories are 6.8%, 6.3%; repeatability limits are 2 µg/L and 14 µg/L; reproducibility limits are 2 µg/L and 22 µg/L.

Six laboratories performed 6 repeated determinations of groundwater samples with spiked concentrations of 10 µg/L and 100 µg/L.

The relative standard deviations in the laboratories are 3.3% to 9.8% and 1.3% to 3.8%; the relative standard deviations in the laboratories are 5.1%, 4.8%; repeatability limits are 2 µg/L and 9 µg/L; reproducibility limits are 2 µg/L and 16 µg/L.

Six laboratories performed 6 repeated determinations of glyphosate spiked domestic sewage samples at 10 µg/L and 100 µg/L.

The relative standard deviations in the laboratory were 3.2% to 7.6% and 2.7% to 7.4%; the relative standard deviations between the laboratories were 6.1%, 8.4%; repeatability limits are 2 µg/L and 14 µg/L; reproducibility limits are 2 µg/L and 26 µg/L.

min

Six laboratories spiked industrial wastewater (glyphosate production) at concentrations of 10 µg/L, 100 µg/L, and 1000 µg/L Wastewater total discharge port) samples were tested 6 times repeatedly. the relative standard deviations in the laboratory were 2.4% ~ 9.5%, 3.5% ~ 7.8%, 1.6% to 8.4%; relative standard deviations between laboratories were 7.6%, 4.8%, and 8.4%; repeatability limits were 2 µg/L, 15 µg/L, 143 µg/L; reproducibility limits are 3 µg/L, 19 µg/L, and 265 µg/L.

The six laboratories separately treated industrial wastewater containing glyphosate at an average concentration of 15 µg/L (the outlet of the glyphosate production wastewater workshop).

Six replicates were spiked at 10 µg/L and 100 µg/L. the relative standard deviations in the laboratory were 0.8% to 9.8%, 2.2% ~ 4.7%, 0.9% ~ 6.5%; the relative standard deviations among laboratories are 8.4%, 4.3%, and 6.9%, respectively;

They are 2 µg/L, 3 µg/L, 12 µg/L; the reproducibility limits are 4 µg/L, 4 µg/L, and 24 µg/L.

10.2 Accuracy

Six laboratories analyzed and measured surface water samples with spiked concentrations of 10 µg/L and 100 µg/L. spiking the recoveries were 91.5% ~ 106%, 92.9% ~ 109%, and the final recoveries were 97.4% ± 13.0%, 98.7%.

± 12.4%.

Six laboratories have analyzed and measured glyphosate groundwater samples with spiked concentrations of 10 µg/L and 100 µg/L.

The recoveries were 89.4% to 103%, 92.9% to 107%, and the final recoveries were 98.7% ± 10.2% and 100%.

Six laboratories analyzed and analyzed glyphosate for domestic sewage samples with spiked concentrations of 10 µg/L and 100 µg/L.

The standard recovery rates are 88.5% to 105%, 85.0% to 108%, and the final recovery rates are 97.7% ± 12.0%, 97.6%.

± 16.6%.

Six laboratories spiked industrial wastewater (glyphosate production) at concentrations of 10 µg/L, 100 µg/L, and 1000 µg/L the total waste water outlet) samples were analyzed and determined. the spiked recovery rates were 84.6% to 105%, 92.3% to 106%, and 89.7% to 111%, the final recoveries were 96.6% ± 14.4%, 98.9% ± 9.4%, 97.9% ± 16.8%.

The six laboratories separately treated industrial wastewater containing glyphosate at an average concentration of 15 µg/L (the outlet of the glyphosate production wastewater workshop).

Analyzed and spiked at 10 µg/L and 100 µg/L. The recoveries were 87.0% ~ 108%, 87.7% ~ 107%, the final recoveries were 97.7% ± 15.4% and 95.8% ± 13.4%.

11.1 Blank test

At least one blank test shall be performed every 20 samples or each batch (less than 20 samples/batch).

Legal detection limit.

11.2 Calibration

Before analyzing samples, a working curve covering at least 5 concentration points in the sample concentration range should be established.

The number of relationships should be >=0.995. Every 20 samples or each batch (less than 20 samples/batch), a standard series intermediate concentration should be determined Point, the relative error between the measurement result and the concentration of this point in the working curve should be within ± 20%. Otherwise, a new work song should be created line.

11.3 Parallel samples

Every 20 samples or each batch (less than 20 samples/batch) should take one parallel sample, and the relative deviation of parallel samples should be <=20%.

11.4 Matrix Spiking

Every 20 samples or each batch (less than 20 samples/batch) should be analyzed with a matrix plus standard sample.

The yield should be between 70% and 130%.