HJ1017-2019Water quality - Determination of benzidine - High performance liquid chromatography (English PDF)

6.1 Sample collection and preservation

Sample collection was performed in accordance with the relevant regulations of HJ/T 91 and HJ/T 164. Add to the vial (5.3) before sampling Sodium thiosulfate (4.5) was added and 40 mg was added per 500 ml of sample. When sampling, the sample should be filled with the sample bottle, leaving no liquid on the space. If the pH of the sample is not between 6 and 9, adjust with hydrochloric acid solution (4.11) or sodium hydroxide solution (4.15).

pH to 6-9. The collected samples should be stored at 4 ° C or less, stored in the dark, and extracted within 5 days. The extracted eluate at 4 ° C the following refrigerated and protected from light, the analysis was completed within 4 days.

6.2 Preparation of samples

6.2.1 Activation of solid phase extraction column

The solid phase extraction column (4.21) was fixed on a solid phase extraction unit (5.7) with 5 ml of methanol (4.8) for about 2 ml/min.

The flow rate is passed through a solid phase extraction column. Before the filler is exposed to air, 5 ml of water is added to the column until the water is about 2 ml.

Stop activation.

6.2.2 Enrichment, purification and concentration

Measure 150 ml of the sample in a 250 ml Erlenmeyer flask and pass the activated solid phase extraction column at a flow rate of approximately 2 ml/min.

(6.2.1) After the sample is completely enriched, add 5 ml of acetic acid solution (4.14). After the acetic acid solution is completely discharged, add 8 ml.

The methanol (4.8) was rinsed, and after the methanol completely flowed out, the vacuum pump was used for 5 minutes. Use 7 ml ammonia solution in methanol (4.16) Elution was carried out and the eluate was collected into a concentrate bottle. The flask was then placed on a nitrogen blower (5.5) and concentrated to 1 ml at 60 °C.

The volume was adjusted to 2.0 ml with water, mixed and filtered through a filter (4.22) into a brown sample vial for testing.

Note. For samples with a suspended solids concentration of more than 12 mg/L, the sample can be adjusted to a pH of about 3 with a hydrochloric acid solution (4.11).

The sonic cleaner (5.6) was sonicated for 10 min and filtered through a filter (4.22) infiltrated with ethanol (4.9). The filtrate is dissolved in sodium hydroxide the liquid (4.15) was adjusted to pH 6-9 and subjected to solid phase extraction.

6.3 Preparation of blank samples

The test sample was used to replace the sample, and the preparation of the blank sample was carried out in the same manner as in the preparation of the sample (6.2).

7.1 Chromatographic Reference Conditions

Mobile phase A. acetonitrile (4.10), mobile phase B. ammonium acetate solution (4.13); elution procedure is isocratic elution, flow Phase A/mobile phase B=20/80 (V/V), flow rate. 1.0 ml/min; column temperature. 40 ° C; excitation wavelength. 292 nm, detection Wavelength. 395 nm; injection volume. 40.0 µl.

7.2 Establishment of calibration curve

Take appropriate amount of benzidine standard use solution I (4.19) or benzidine standard use solution II (4.20), with methanol water Dilute the solution (4.12) to prepare a standard series of at least 5 concentration points. The mass concentration of benzidine is 2.00 µg/L, 5.00 µg/L, 10.0 µg/L, 50.0 µg/L, 100 µg/L,.200 µg/L (this is the reference concentration). According to the chromatographic reference strip (7.1), the standard series solution is injected sequentially from low to high concentration, and the mass concentration (µg/L) of benzidine is on the abscissa, the corresponding peak area or peak height is plotted on the ordinate to establish a calibration curve.

7.3 Determination of samples

The measurement of the sample (6.2.2) was carried out under the same conditions as the establishment of the calibration curve (7.2).

7.4 Blank test

The blank sample (6.3) was measured under the same conditions as the measurement (7.3) of the sample.

8.1 Qualitative analysis

Qualitative according to the retention time of the target compound in the sample and the target compound in the standard series, different wavelengths can be used the fluorescence intensity below is more qualitatively defined and, if necessary, confirmed by high performance liquid chromatography-triple quadrupole mass spectrometry.

The standard chromatogram of benzidine is shown in Figure 1 under the chromatographic reference conditions (7.1) recommended in this standard.

Figure 1 Standard chromatogram of benzidine (rho = 50.0 µg/L)

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1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 min 0.00 mAU

8.2 Quantitative analysis

The mass concentration of benzidine in the sample rho (µg/L), calculated according to formula (1).

DVrho

= 11 (1)

Where. rho--the mass concentration of benzidine in the sample, µg/L;

1-1-- mass concentration of benzidine in the sample obtained from the calibration curve, µg/L;

V1--sample volumetric volume, ml;

V--sampling volume, ml;

D--dilution factor.

8.3 Result representation

When the measurement result is less than 1 µg/L, the three decimal places are retained; when the measurement result is greater than or equal to 1 µg/L, the retention is retained.

Three valid figures.

9.1 Precision

6 laboratories were applied to surface water samples with a concentration of benzidine spiked at 0.027 µg/L, 0.267 µg/L and 1.06 µg/L.

6 repeated measurements. the relative standard deviations in the laboratory were 1.9% to 7.2%, 1.7% to 7.5%, and 1.7% to 6.3%, respectively;

The relative standard deviations between laboratories were 8.8%, 5.5%, and 7.5%, respectively; the repeatability limits were 0.003 µg/L, 0.032 µg/L, and 0.11 µg/L; reproducibility limits are 0.006 µg/L, 0.047 µg/L and 0.23 µg/L.

Six replicates of 6 samples of domestic wastewater containing benzidine spiked at 0.267 µg/L were tested in 6 laboratories. experiment the indoor relative standard deviation is 3.4% to 6.6%; the relative standard deviation between laboratories is 6.6%; the repeatability limit is 0.038 µg/L;

The reproducibility limit was 0.057 µg/L.

Industrial wastewater samples with an average concentration of 0.462 µg/L of biphenylamine and a spiked concentration of 0.500 µg/L in 6 laboratories Six repeated measurements before and after the spike were performed. the relative standard deviations in the laboratory were 1.4% to 7.0% and 1.1% to 5.3%, respectively;

The relative standard deviations between laboratories were 8.1% and 4.5%, respectively; the repeatability limits were 0.062 µg/L and 0.095 µg/L; reproducibility the limits are 0.12 µg/L and 0.15 µg/L.

9.2 Accuracy

6 laboratories were applied to surface water samples with a concentration of benzidine spiked at 0.027 µg/L, 0.267 µg/L and 1.06 µg/L.

Six times of repeated spike analysis showed that the recoveries ranged from 73.9% to 95.1%, 80.6% to 98.4%, and 84.0%, respectively.

97.0%; the final recoveries were 88.0% ± 15.8%, 88.2% ± 12.4% and 91.0% ± 10.0%.

6 laboratories performed six repeated spikes on the domestic sewage samples with a concentration of 0.267 µg/L of benzidine.

The recovery rate of the spiked standard ranged from 83.8% to 100%; the final value of the spiked recovery was 90.3%±11.2%.

Industrial wastewater samples with an average concentration of 0.462 µg/L of biphenylamine and a spiked concentration of 0.500 µg/L in 6 laboratories Six times of repeated spike analysis were carried out. the recoveries ranged from 86.6% to 102%; the final value of the spiked recovery was 93.7% ± 10.6%.

10.1 Blank test

At least one laboratory blank should be made for every 20 samples or batches (<=20 samples/batch) and the results should be below the square Law detection limit.

10.2 Calibration

The correlation coefficient of the calibration curve should be >=0.999. One should be determined for every 20 samples or batches (<=20 samples/batch) for the standard solution of the intermediate concentration point of the calibration curve, the relative error between the measurement result and the concentration of the curve at this point should be within ±15%.

10.3 Parallel samples

At least one parallel sample should be measured for every 20 samples or batches (<=20 samples/batch). The relative deviation of the parallel samples should be <=20%.

10.4 Matrix addition

At least one matrix spiked sample shall be determined for every 20 samples or batches (<=20 samples/batch), and the spiked recovery rate shall be Between 70% and 120%.