GB 29708-2013Determination of Sodium Pentachlorophenol residues in animal derived food by Gas Chromatography-mass Spectrometric method (English PDF)

6.1 Preparation of the sample

Fresh or thawed take appropriate blank or test tissue, minced, and homogenized.

--- homogeneous test sample taken, as the feed try.

--- the blank sample were homogeneous, as a blank sample.

--- blank sample taken homogeneous, standard working solution is added an appropriate concentration, is added as a blank sample.

Save 6.2 sample

-20 °C less storage backup.

Determination Step 7

7.1 Preparation of matrix-matched standard curve

Accurately taken 2µg/mL sodium pentachlorophenol appropriate amount of working standard solution, prepared with water to a concentration of 2,5,10,20,50,100µg/L series Standard solution from each 1.0 mL, extracted separately dissolved, after drying 6 parts distilled white residue sample, mixed, dissolved with 2.4mol/L hydrochloric acid PH was adjusted to less than 2.0, add cyclohexane - ethyl acetate solution 5mL, vortexed, 8000r/min centrifugal 10min, the organic layer was pipetted and then Adding cyclohexane - ethyl acetate solution 5mL, the organic layer was twice vortex mixed, 8000r/min centrifugal 10min, combined, rotary evaporated at 45 °C dry. By derivatization steps, gas chromatography mass spectrometry. A characteristic ion mass chromatogram peak area for the vertical axis, the concentration control solution of Abscissa, the standard curve. Seeking regression equation and correlation coefficient.

7.2 Extract

Sample Weigh 5g ± 0.05g, in 50mL centrifuge tubes, add water 10mL, Vortex, 8000r/min centrifugal 10min, supernatant Solution, 5% trichloroacetic acid was added 5mL, Vortex, 8000r/min centrifugal 10min, the supernatant was adjusted to pH with 2.4mol/L hydrochloric acid solution to less than 2.0, add cyclohexane - ethyl acetate solution 5mL, vortexed, 8000r/min centrifugal 10min, the organic layer was pipetted, cyclohexyl plus Alkoxy - ethyl acetate solution 5mL, vortexed, 8000r/min centrifugal 10min, the two organic layers were combined, rotary evaporated to dryness at 45 °C.

7.3 Derivatized

The residue was added cyclohexane - ethyl acetate, 1.0 mL, was added a small amount of anhydrous sodium sulphate, was added acetic anhydride - pyridine solution, 100 L, sealed and 60 °C reaction 15min, cooled and 0.5 mL potassium carbonate solution was added, mixed thoroughly, left to stand stratification, the organic phase, gas chromatography mass spectrometry.

7.4 Determination

7.4.1 Chromatographic conditions

7.4.1.1 Column. DB-5MS5% phenylmethyl polysiloxane (30m × 0.25mm, film thickness 0.25µm), or equivalent person.

7.4.1.2 Inlet temperature. 250 °C.

7.4.1.3 Injection mode. splitless.

7.4.1.4 Injection volume. 2µL.

7.4.1.5 Column temperature. initial temperature 140 °C, retention 2min, at 10 °C/min was heated to 200 °C, at 15 °C/min was heated to 280 °C, maintained 3.0min.

7.4.1.6 Carrier gas. Helium, 1.0mL/min (constant).

7.4.2 MS conditions

7.4.2.1 EI Source. 70eV.

7.4.2.2 Solvent delay. 3min.

7.4.2.3 GC/MS transfer line temperature. 280 °C.

7.4.2.4 selected ion monitoring mode, detect ions Sim (m/z). 266,308,237,165,130.

7.4.2.5 quantitative ion. 266.

7.4.3 Assay

By retention time and the retention time of the standard solution sample chromatogram, the peaks corresponding to the characteristic ions of each standard concentration Chromatography in contrast to the qualitative characteristics of ion peaks. Relative abundance compared to the relative abundance of ions in the sample solution with the matrix matching criteria ions in solution, in accordance with Table 1. Matrix-matched standard solution and test solution was added mass chromatogram characteristic ions are given in Appendix A.

Table 1 sample solution ion relative abundance of the tolerance range

The relative abundance Tolerance > 50 ± 20 > 20 ~ 50 ± 25 > 10 ~ 20 ± 30 <=10 ± 50

7.5 Blank test

Measure the blank sample assay step is performed in exactly the same operation in parallel.

Calculation and Expression of Results 8 Single-point calibration.

cSA

Or matrix-matched standard curve calibrated by. AS = acS b to obtain a and b, then c = Ab (2) the specimens residual amount of sodium pentachlorophenol (µg/kg) (3) is calculated according to the formula.

Where.

C --- try to supply feed solution of pentachlorophenol sodium concentration, in units of nanograms per milliliter (ng/mL);

cS --- pentachlorophenol sodium concentration, expressed in nanograms per milliliter (ng/mL) in standard solution;

A --- try to supply feed solution of the peak area of sodium pentachlorophenol derivative;

--- the AS standard solution of sodium pentachlorophenol derivative peak area;

X-try for feed Residue --- sodium pentachlorophenol, in micrograms per kilogram (µg/kg);

The residue was V --- constant volume in milliliters (mL);

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 0.25µg/kg.

The limit of quantitation of the method, the muscle tissue was 0.5µg/kg, liver and kidney tissues was 1µg/kg.

9.2 Accuracy

In the process of muscle tissue 0.5µg/kg ~ 2µg/kg, liver and kidney tissues at 1µg/kg ~ 4µg/kg was added on the concentration level Recoveries of 60% to 120%.

9.3 Precision

<=20% relative standard deviation in this method and inter - batch relative standard deviation of <=20%.

Appendix A

Chromatogram

Figure A.1 standard solution wherein sodium pentachlorophenol ion mass chromatogram (2µg/L)

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

Figure A.3 pig liver tissue sample blank add characterized pentachlorophenol sodium ion mass chromatogram (1µg/kg)