GB 23200.86-2016Food safety national standard -- Determination of residues of organochlorine pesticides in milk and dairy products by gas chromatography-mass spectrometry / mass spectrometry (English PDF)

4.1 Reagents

4.1.1 n-hexane (C6H14). chromatographic purity.

4.1.2 Acetone (C3H6O). Chromatographic pure.

4.1.3 dichloromethane (C2H2Cl2). chromatographic purity.

4.1.4 Cyclohexane (C6H12).

4.1.5 Ethyl acetate (C4H8O2).

4.1.6 anhydrous sodium sulfate (Na2SO4). 650 °C burning 4 h, in the dryer to cool to room temperature, stored in a sealed bottle in reserve.

4.1.7 Sodium chloride (NaCl).

4.2 Solution preparation

4.2.1 Extract. Take appropriate n-hexane and acetone in a 1. 1 by volume ratio.

4.2.2 Gel permeation chromatography Eluent. Take appropriate amount of cyclohexane and ethyl acetate in a 1. 1 by volume ratio.

4.2.3 Solid Phase Extraction Eluent. Take appropriate n-hexane and dichloromethane in a volume ratio of 5.95.

4.3 Standards

4.3.1 Pesticide Reference Material. Purity >=95%.

4.4 Standard solution preparation

4.4.1 standard stock solution. accurately weighed the right amount of the standard material, with n-hexane prepared into a concentration of 100 µg/mL standard stock solution, the solution was stored at 0 ° C to 4 ° C in the dark.

4.4.2 standard intermediate solution. take appropriate amount of standard stock solution, prepared into a 2 µg/mL mixed standard working solution, the solution in the 0 °C ~ 4 °C dark preservation.

4.4.3 standard working solution. take appropriate amount of various standard stock solution, prepared into the appropriate concentration of mixed standard working solution. Standard work Liquid is now available.

4.5 Materials

4.5.1 Florisil Solid Phase Extraction Column. 1 g/6 mL, or equivalent, activated with 5 mL n-hexane prior to use.

4.5.2 Microporous membrane. 0.45 µm, organic.

7.1 Extraction

Accurately weigh 10 g of sample (accurate to 0.01 g) in a 50 mL stoppered centrifuge tube (milk powder, lactose plus 10 mL of water), add 5 g of sodium chloride, add 10 mL of the extract, shake with a vortex mixer for 1 min, 4 000 r/min for 3 min, transfer the organic phase to 100 mL of rotary vials, the residue was extracted twice with 10 mL of the extract, the organic phase was centrifuged and concentrated by rotary evaporation at 40 ° C Close to dry, with 10 mL cyclohexane - ethyl acetate mixed solution to fully dissolve the residue, over 0.45 µm filter, to be purified.

7.2 Purification

7.2.1 Purification by gel permeation chromatography

7.2.1.1 Reference conditions

A) Purification column. 400 mm × 25 mm (id), containing Bio-Beads, S-X3, 38 µm ~ 75 µm filler, or equivalent performance.

B) mobile phase. cyclohexane-ethyl acetate (1 1, volume ratio);

C) Flow rate. 5 mL/min;

D) Injection volume. 5 mL;

E) Start collection time. 10 min;

F) End of collection time. 22 min.

7.2.1.2 Purification steps

The solution to be purified was transferred to a 10 mL test tube and purged with a gel permeation chromatograph. The eluent was collected for 10 min to 22 min at 40 ° C and then concentrated to about 2 mL under reduced pressure to be purified by Fryborough silica solid phase extraction column.

7.2.2 Solid phase extraction purification

The sample was transferred to an activated florisil silica solid phase extraction column and the effluent was collected and washed with 8 mL of dichloromethane-n-hexane solution the eluate was collected by rotary evaporation at 40 ° C and concentrated to near dryness. The residue was dissolved in 1 mL of n-hexane and passed through a 0.45 µm filter for assay. The

7.3 Determination

7.3.1 Instrument reference conditions

A) Column. TR-35 ms, 30 m × 0.25 mm × 0.25 µm, or equivalent;

B) Column temperature. 55 °C for 1 min, at 40 °C/min rate rose to 140 °C, keep 5 min, at 2 °C/min rate rose to 210 °C, to 10 °C/min rate rose to 280 °C, keep 10 min;

C) Inlet temperature. 250 ° C;

D) ion source temperature. 250 ° C;

E) Transmission line temperature. 250 ° C;

F) ion source. electron bombardment ion source;

G) Measurement method. Select the reaction monitoring mode (SRM);

H) Monitoring ions (m/z). Qualitative ion pairs, quantitative ion pairs, collision energy and ion abundance of various organochlorine pesticides are given in Appendix A in Table A.1;

I) Carrier gas. helium, purity not less than 99.999%;

J) Flow rate. 1.2 mL/min;

K) Injection method. no shunt;

L) Injection volume. 1 µL;

M) Ionization energy. 70 eV;

7.3.2 Determination and confirmation of chromatography

Determination of sample solution and standard working solution according to 7.3.1 gas chromatography-mass spectrometry/mass spectrometry conditions, determination of organochlorine pesticide residues in sample solution by external standard method the amount. Residues to be measured in the sample should be within the standard curve, and if the residue exceeds the standard curve range, appropriate dilution should be made. in the retention times of the various organic chlorine mass chromatographic peaks under the above chromatographic conditions are given in Table A.1 in Appendix A. The total ion chromatogram of the standard and the multiple the chromatogram should be shown in Figure B.1 and Figure B.2 in Appendix B.

Under the same experimental conditions, the relative retention time of the sample and the mass chromatographic peak of the test substance in the standard working fluid was within ± 2.5% and in the sample quality chromatogram after subtracting the background, the selected ion pair appears, and the relative abundance of the standard is not allowed the range specified in Table 1, you can determine the existence of the corresponding sample in the sample.

Table 1 Gas Chromatography - Tandem Mass Spectrometry Qualification Relative Relative Absorption Error of Ion Abundance

Relative abundance (base) 50% 20% to 50% 10% to 20% <=10% Allowable relative deviation ± 20% ± 25% ± 30% ± 50%

7.4 Blank test

In addition to weighing the sample, according to the above steps.

10.1 Quantitation limits

The limit of quantification of various organochlorine pesticides in this method was 0.8 µg/kg.

10.2 Recovery rate

The average recoveries of the method were 62.2% ~ 116.8%.

Appendix A

(Informative)

Reference mass spectrometry conditions 1 Mass spectrometry conditions.

A) Method mode. EZ method B) ion box. CEI (Close EI) C) ion source temperature. 250 ° C D) filament current. 25 µA E) Q1 peak width. 0.7 FWHM F) Cycle time. 0.5 s G) chromatographic filter peak width. 3.0 s H) collision gas. argon, the purity of not less than 99.999% I) Collision gas pressure. 1.5 mTorr J) Qualitative ion pair, quantitative ion pair, collision energy and ion abundance ratio are shown in Table A.1.

Table A.1 Retention Time of 30 Organochlorine Pesticides, CAS, Qualitative Ion Pair, Quantitative Ion Pair and Collision Energy

Time window

(Min)

Compounds

keep time

(Min)

CAS parent ion (m/z) Ion (M/z) Collision energy (EV) Qualitative/quantitative ion Abundance ratio (%) 13.0 to 25.0 Tetrachloronitrobenzene 15.9 117-18-0 259.201 15 261 203 * 15 Hexachlorobenzene 19.6 608-73-1 286 251 * 20 Alpha 666 20.5 319-84-6 181 145 * 15 Pentachloronitrobenzene 23.2 82-68-8 295 237 * 20 Lindane 24.0 58-89-9 181 145 * 15 25.0 to 33.0 BHC 6 26.3 319-85-7 181 145 * 15 Heptachlor 27.1 76-44-8 272 237 * 15 Pentachloroaniline 27.8 527-20-8 265 158 * 30 delta-six six six 28.8 319-86-8 181 145 * 15 Aldrin 29.9 309-00-2 263 193 * 32 Methyl pentachlorophenyl sulfide 31.3 1825-19-0 296 263 * 20 61

Table A.1 Retention Time, CAS, Qualitative Ion Pair, Quantitative Ion Pair and Collision Energy of 30 Organochlorine Pesticides (Continued)

1 Non-commercial declaration. The reference mass spectrometry conditions listed in Appendix A are performed on a thermo TSQ Quantum GC GC-Tandem Mass Spectrometer, listed here the test instrument model is for reference only and does not involve commercial purposes and encourages standard users to try different manufacturers or models of instruments.

Oxidized Chlordane 34.1 27304-13-8 387 263 * 15 74 Epoxy heptachlor 35.2 28044-83-9 353 253 * 15 58 Trans-chlordane 37.2 5103-74-2 373 266 * 18 Cis-chlordane 38.3 5103-71-9 373 266 * 18 O, p'-drop i 38.4 72-55-9 246 176 * 25 Alpha-endosulfan 38.4 959-98-8 241 206 * 20 39.5 to 45.3 P, p'-droplet 40.5 72-55-9 246 176 * 25 Dieldrin 40.5 60-57-1 263 193 * 26 O, p'-drop 41.1 53-19-0 235 165 * 20 Endrin 41.9 72-20-8 263 193 * 26 O, p'-DDT 42.6 789-02-6 235 165 * 20 P, p'-drop 43.0 72-54-8 235 165 * 20 Beta-endosulfan 43.0 33213-65-9 241 206 * 20 P, p'-DDT 43.9 789-02-6 235 165 * 20 Aldin Aldehydes 43.9 7421-93-4 345 317 * 10 Endosulfan sulfate 44.5 1031-07-8 272 237 * 15 45.3 ~ 48.0 Methanol DDT 46.1 72-43-5 227 169 * 20 Endrin Ketone 46.2 53494-70-5 317 281 * 10 Mirex 46.6 2385-85-5 272 237 * 15 Note. "*" Quantitative ions.

Appendix A

(Informative)

Chromatogram

RT. 0.00 - 47.31

0 5 10 15 20 25 30 35 40 45 Time (min) La Ti 41.45 42.65 43.00 43.95 46.63 38.36 46.15 27.14 37.15 19.55 31.32 29.9015.94 24.0723.26 35.1816.07 23.19 34.15 NL.

1.75E4

TIC MS

091024-

4ppb-2

Figure B.1 Total ion chromatogram of 30 organochlorine pesticide standard solutions (4 µg/L)

Tetrachloronitrobenzene RT. 10.27 - 20.13 Time (min) La Ti E RT. 15.90 RT. 15.91 Hexachlorobenzene RT. 16.33 - 22.08 Time (min) La Ti E RT. 19.57 RT. 19.56 Six six six (alpha/nu/beta/delta) RT. 18.47 - 30.44 Time (min) La Ti E RT. 28.75 RT. 26.27 RT. 24.05 RT. 28.76 RT. 26.29 RT. 20.54 RT. 20.32 - 28.81 Time (min) La Ti E RT. 23.22 RT. 23.24 Pentachloronitrobenzene heptachlor RT. 22.01 - 31.74 Time (min) La Ti E RT. 27.11 RT. 27.12 Pentachloroaniline RT. 23.35 - 32.66 24 26 28 30 32 Time (min) La Ti E RT. 27.75 RT. 27.72 Aldrin RT. 25.81 - 33.85 Time (min) La Ti E RT. 29.90 RT. 29.90 Pentachlorophenyl sulfide RT. 25.81 - 33.85 Time (min) La Ti E RT. 31.27 RT. 31.26 Oxidized Chlordane RT. 30.18 - 38.92 Time (min) La Ti E RT. 34.15 RT. 34.10 Epichlorohydrin RT. 30.18 - 38.92 Time (min) La Ti E RT. 35.20 RT. 35.18 Chlordane (trans/cis) RT. 34.51 - 40.43 Time (min) La Ti E RT. 37.15 RT. 38.30 RT. 37.16 RT. 38.27 DDE (op/pp) RT. 36.47 - 41.70 37 38 39 40 41 Time (min) La Ti E RT. 40.50RT. 38.36 RT. 38.93 RT. 40.48 RT. 38.36 RT. 38.66

Figure B.2 Selection of 30 Organochlorine Pesticide Standard Solutions Response Monitoring (SRM) Ion Chromatography

Endosulfan (alpha/beta) RT. 33.69 - 46.04 Time (min) La Ti E RT. 43.01 RT. 38.45 RT. 38.43 RT. 43.00 Dieldrin RT. 38.32 - 41.74 Time (min) La Ti E RT. 40.54 RT. 40.54 O, p '(DDD, DDT, p), p (DDD DDT) RT. 40.26 - 44.90 Time (min) La Ti E RT. 43.93RT. 42.63 RT. 42.98 RT. 41.43 RT. 43.93 RT. 42.63 RT. 42.98 RT. 41.43 Endrin RT. 40.80 - 45.70 41 42 43 44 45 Time (min) La Ti E RT. 41.96 RT. 41.94 Aldin aldehydes RT. 40.80 - 45.70 41 42 43 44 45 Time (min) La Ti E RT. 43.89 RT. 43.90 RT. 44.10 Endosulfan sulfate RT. 40.87 - 46.30 41 42 43 44 45 46 Time (min) La Ti E RT. 44.51 RT. 43.01 RT. 46.24 RT. 44.49 Methanol DDT RT. 40.30 - 47.31 Time (min) La Ti E RT. 46.12 RT. 46.12 Vitamin ketone RT. 44.31 - 47.30 Time (min) La Ti E RT. 46.24 RT. 46.64 RT. 46.24 Mirex RT. 44.31 - 47.30 Time (min) La Ti E RT. 46.63 RT. 46.64 RT. 44.51 RT. 46.24RT. 44.68 Appendix B (Normative appendix) Laboratory repeatability requirements

Table B.1 Laboratory repeatability requirements

Measured component content Mg/kg Precision <=0.001 36 > 0.01 > 1 14 Appendix C (Normative appendix) Inter-laboratory reproducibility requirements

Table C.1 Inter-laboratory reproducibility requirements

Measured component content Mg/kg Precision <=0.001 54 > 0.01 > 1 19