GB 29706-2013Determination of Dapsone residues in animal derived food by Liquid Chromatography-tandem Mass Spectrometric method (English PDF)

6.1 Preparation of the sample

Fresh or frozen blank or test tissue, minced, and homogenized.

--- the test sample taken after homogenization, as the feed try.

--- blank sample taken after homogenization, as a blank sample.

--- blank sample taken after homogenization, adding a suitable concentration of the standard working solution, is added as a blank sample.

Save 6.2 sample

Or less at -20 °C.

Determination Step 7

7.1 Extract

Sample Weigh 2g ± 0.05g, a centrifuge tube, acetonitrile was added 10mL, vortexed 2min, n-hexane was added 5mL, vortexed 1min, ultrasonic 5min, 5000r/min centrifugal 10min, discard the upper layer of n-hexane solution. Acetonitrile was taken to another centrifuge tube, was added 1mol/L Hydrochloric acid solution 10mL, Vortex, spare.

7.2 Purification

MCX column washed with 5mL methanol and 5mL water activation, taking stock solution through the column, controlling the flow rate of less than 1mL/min, with 0.1mol/L 5mL methanol and 5mL solution of hydrochloric acid rinsed, drained, eluting with 5% ammoniated 5mL acetonitrile, dry nitrogen at 40 °C water bath, mobile phase the residue was dissolved 1.0mL, Vortex for liquid chromatography - tandem mass spectrometry.

7.3 Preparation of standard curve

The precise amount of 100ng/mL working standard solution amount dapsone, diluted with methanol, concentrations were formulated and 0.5,1,2,5,10 20µg/L standard solution series. For liquid chromatography - tandem mass spectrometry. A characteristic ion mass chromatogram peak area for the vertical axis, control solution Concentration as the abscissa, the standard curve, seeking regression equation and correlation coefficient.

7.4 Determination

7.4.1 LC Conditions

7.4.1.1 Column. C18 (150mm × 2.1mm, particle size 5µm), or equivalent person.

7.4.1.2 mobile phase. acetonitrile 5mmol/L ammonium acetate (50 50, volume ratio).

7.4.1.3 Column temperature. 40 °C.

7.4.1.4 Injection volume. 20µL.

7.4.2 MS conditions

7.4.2.1 Ion Source. ESI source.

7.4.2.2 Scan mode. positive ion scan.

7.4.2.3 Detection mode. selective reaction monitoring.

7.4.2.4 Spray voltage. 4800V.

7.4.2.5 Ion transfer tube temperature. 350 °C.

7.4.2.6 Sheath Gas Pressure. 40arb.

7.4.2.7 Auxiliary gas pressure. 5arb.

7.4.2.8 dapsone optimization parameters selected reaction monitoring. Table 1.

Table 1 dapsone selected reaction monitoring of optimization parameters

Drug Name qualitative and quantitative ion ion pair Collision energy eV Dapsone 249.0 > 108.1 249.0 > 92.2 249.0 > 108.1 21 twenty three

7.4.3 Determination

7.4.3.1 Qualitative determination

By retention time of sample chromatogram with retention times of the respective standards, wherein each of the ion peaks and the corresponding concentration of the standard Wherein each of the ion peaks qualitative contrast. Sample and standard deviation of the relative retention time of not more than 5%; with a sample wherein ions Consistent with the abundance relative abundance fairly mixed standard solution concentration, relative abundance does not exceed a predetermined deviation Table 2, the sample can be stored is determined the respective analyte.

The maximum allowable deviation relative ion abundance qualitative determination of Table 2 the relative ion abundances > 50 20 ~ 50 10 ~ 20 <=10 Permissible relative deviation ± 20 ± 25 ± 30 ± 50 Ratio for the sample and standard solutions try quantitative ion area of single-point calibration for quantification.

7.4.3.2 Quantitative determination

Take a sample and standard solutions, by external standard method, in order to quantify the peak area, the standard solution and the sample solution response value should be at dapsone the linear range of the detection equipment. In the above-described chromatography - mass spectrometry under conditions dapsone standard solution, the tissue sample and the blank sample blank add organizations the ion mass chromatogram of the sample solution in Appendix A.

7.5 Blank test

But without addition of the sample, the same steps employed in parallel operation.

Calculation and Expression of Results 8 the residual amount of ammonia present the sample of the sulfone (µg/kg) according to formula (1).

A × cS × V

AS × m

Where.

--- try feed for X-sulfone remaining amount of ammonia present in units of micrograms per kilogram (µg/kg);

A --- peak area of sample solution of ammonia present sulfone;

cS sulfone --- ammonia concentration present in the standard working solution, in micrograms per liter (µg/L);

V --- The residue was dissolved with the volume of mobile phase, milliliters (mL);

--- the AS standard working solution of ammonia present peak area sulfone;

m --- try supply feed mass in grams (g).

Note. The blank value should be subtracted from the results, expressed as the arithmetic mean of the measurement result measured parallel to three significant figures.

9.1 Sensitivity

The detection limit of the method was 0.1µg/kg, the limit of quantitation was 0.5µg/kg.

9.2 Accuracy

This method of adding 0.5µg/kg ~ 2µg/kg on recovery levels of 60% to 120%.

9.3 Precision

<=30% relative standard deviation in this method and inter - batch relative standard deviation of <=30%.

Appendix A

Chromatogram

Figure A.1 ammonia standard solution wherein the sulfone of the present ion mass chromatogram (0.5µg/L)

Figure A.2 wherein the sample blank pig liver tissue ion mass chromatogram

Figure A.3 pig liver tissue sample blank add ammonia present sulfones wherein the ion mass chromatogram (0.5µg/kg)