HJ 849-2017Water quality - Determination of ethylenethiourea - High performance liquid chromatography (English PDF)

7.1 Sample collection and storage

Samples were collected according to the relevant regulations of HJ/T 91 and HJ/T 164. The collected water samples should be refrigerated at 4 ° C, protected from light and sealed Save, within 30 d analysis is completed.

7.2 Sample preparation

The water sample was filtered through a 0.22 µm filter (6.5) and placed in a vial and tested.

Note. For samples containing organic matter, take 10 ml of water samples, with 2 ml of n-hexane extraction, take the water phase for determination.

7.3 Blank sample preparation

The sample was prepared in the same manner as in Sample Preparation Step (7.2).

8.1 Chromatographic reference conditions

Mobile phase A. methanol; mobile phase B. water; flow rate. 0.8 ml/min; column temperature. 30 °C; detection wavelength. 233 nm;

Injection volume. 20 µl. The elution procedure is shown in Table 1.

Table 1 elution program

Time (min) A (%) B (%) Note. After 6 minutes elution, the cleaning column can be used to clean the column. The cleaning time can be adjusted according to the complexity of the actual sample.

8.2 Calibration curve establishment

Respectively, take appropriate amount of thiodide standard use of liquid (5.4), diluted with water, the preparation of at least five concentrations of the standard series, the concentration of ethylene thiourea was 10.0, 50.0, 250, 500, 1000 µg/L (reference concentration). From low concentration to High concentration followed by the standard series of solution injection to the concentration of ethylene thiourea as the abscissa, the corresponding peak area or peak height Calculate the calibration curve.

8.3 Determination

The sample to be tested (7.2) was subjected to the same conditions as the calibration curve.

38.4 Blank test

The blank sample to be measured (7.3) was measured under the same conditions as the sample.

9 Results calculation and representation

9.1 Qualitative analysis According to the samples in the ethylene thiourea and standard series of ethylene thiourea retention time for qualitative, if necessary, the standard sample Product addition method, absorption ratio at different wavelengths or scanning ultraviolet absorption spectroscopy and other methods to assist qualitative.

Figure 1 shows the chromatograms of the thiourea under the chromatographic conditions recommended in this standard (8.1).

Figure 1 Standard phase chromatogram of ethylene thiourea

9.2 Quantitative analysis the concentration of ethylene thiourea in water samples is calculated according to the following formula.

Where. - mass concentration of ethylene thiourea in water sample, µg/L;

A - the peak area or peak height of ethylene thiourea;

a - the intercept of the calibration curve;

b - the slope of the calibration curve;

f - the dilution factor of the water sample.

9.3 The result is shown when the determination result is greater than or equal to 100 µg/L, the data retained three significant digits; when the determination result is less than 100 µg/L, Reserved to integer bits.

10 precision and accuracy 10.1 precision Six laboratories were tested for white water thiazide with a concentration of 10.0 µg/L, 100 µg/L and 800 µg/L.

The relative standard deviations in the laboratory were 3.0% ~ 9.0%, 0.8% ~ 3.1%, 0.3% ~ 1.1% respectively.

The relative standard deviations were. 8.0%, 5.8%, 3.1%, and the repeatability r was 2 µg/L, 6 µg/L and 17 µg/L, respectively.

The current limit R is. 3 µg/L, 18 µg/L, 72 µg/L.

Six laboratories were tested for surface water spiked with thiodide concentrations of 5.0 µg/L, 10.0 µg/L and 50.0 µg/L for 6 the relative standard deviations in the laboratory were 2.0% ~ 7.5%, 2.7% ~ 9.0%, 0.6% ~ 4.8% respectively.

The relative standard deviations were 8.4%, 10% and 4.6%, respectively. The repeatability r was 1 µg/L, 2 µg/L and 4 µg/L respectively.

The limit R is. 1 µg/L, 3 µg/L, 8 µg/L.

6 laboratories were tested for samples of domesticated sulfur thiourea concentrations of 10.0 µg/L, 50.0 µg/L and 300 µg/L 6 times repeated determination. the relative standard deviation in the laboratory were. 4.0% ~ 9.4%, 0.4% ~ 3.8%, 0.4% ~ 4.1%; real the relative standard deviations were 12%, 9.5% and 12%, respectively. The repeatability r was 2 µg/L, 3 µg/L and 19 µg/L, respectively.

Reproducibility R was. 4 µg/L, 13 µg/L, 107 µg/L.

The concentration of thiourea in the two laboratories was 42 µg/L to 77 µg/L, 241 µg/L to 355 µg/L, 371 µg/L to 589 µg/L industrial wastewater samples were subjected to six repeated measurements. the relative standard deviations in the laboratory were. 2.6% ~ 11%, 0.4% ~ 4.6%, 0.9% ~ 3.8%. The relative standard deviations were 25%, 13% and 15%, the repeatability r was 9 µg/L, 19 µg/L, 20 µg/L, and the reproducibility limit was 41 µg/L, 109 µg/L and 202 µg/L.

10.2 Accuracy

Six labs were divided into two groups. white thiourea concentration of 10.0 µg/L, 100 µg/L and 800 µg/L the recoveries were 100% ~ 120%, 97.0% ~ 113%, 99.0% ~ 108%, respectively. The recoveries were the final Value. 105% ± 16.8%, 103% ± 12.0%, 102% ± 6.4%.

Six laboratories were divided into two groups with samples of surface thalidene thiourea concentrations of 5.0 µg/L, 10.0 µg/L and 50.0 µg/L the recoveries were 80.6% ~ 108%, 85.2% ~ 115% and 93.1% ~ 107%, respectively. The recoveries were the final Values. 98.0% ± 18.4%, 102% ± 19.3%, 100% ± 9.6%.

6 laboratories were tested for samples of domesticated sulfur thiourea concentrations of 10.0 µg/L, 50.0 µg/L and 300 µg/L the recoveries were 80.9% ~ 112%, 87.7% ~ 115%, 95.6% ~ 129%, respectively. The recoveries were the most the final values were 96.6% ± 23.4%, 96.7% ± 18.8% and 104% ± 25.0% respectively.

Six laboratories were tested for industrial waste water with a sample of 25.0 µg/L, 300 µg/L and 500 µg/L the recoveries were 83.3% ~ 104%, 75.2% ~ 109%, 71.1% ~ 112%, respectively. The final recoveries were as follows.

93.8% ± 16.4%, 91.9% ± 21.4%, 91.0% ± 27.0%.

11 quality assurance and quality control 11.1 blank test Every 20 samples or per batch (less than 20 samples) should be at least one lab blank, blank in the thiourea Concentration should be lower than the method detection limit.

11.2 Initial calibration the correlation coefficient of the calibration curve is >=0.995.

11.3 Standard curve verification for every 20 samples or per batch (less than 20 samples), a calibration curve should be measured for the intermediate concentration of the standard solution.

The relative deviation between the result and the concentration of the curve should be <=15%. Otherwise, a new calibration curve should be established.

11.4 parallel samples 5 per 10 samples or per batch (less than 10 samples) should be accompanied by a parallel sample, parallel to the relative deviation of <= 15%.

11.5 matrix spikes

Every 20 samples or each batch (less than 20 samples) need to do a matrix plus standard, the matrix spike recovery rate should be controlled in 70% to 130%.

12 Waste treatment

The organic waste generated in the experiment should be collected and kept collectively and entrusted with qualified units for processing.