AOAC RI Chemical Cont. Methods-2018 Awards

1434 Pang et al.: J ournal of AOAC I nternational V ol. 98, N o. 5, 2015

Table 2014.09B. SIM acquisition parameters by GC/MS for the 20 pesticides of interest in this study Group Start time, min Monitored ions, m / z

Dwell time, ms

1 2 3 4 5 6 7 8 9

14.85 16.85 17.97 19.43 20.00 21.77 22.93 24.20 25.87 28.49

306, 264, 335

80 80 80 40 80 80 80 80 40 40

177, 197, 161, 198, 199, 200 173, 255, 240, 166, 238, 138

154, 230, 203, 285, 287, 270, 265, 267, 250

290, 276, 305

246, 318, 176, 353, 355, 351 359, 303, 357, 318, 316, 246 335, 303, 367, 283, 285, 255

237, 272, 307, 247, 328, 408, 148, 206, 325 181, 166, 165, 266, 394, 267, 341, 183, 339

10

(d)  Homogenizer .—Rotational than 13500 r/min (report also in g -force units; T-25B, Janke & Kunkel, Staufen, Germany), or equivalent. (e)  Rotary evaporator .—Buchi EL131 (Flawil, Switzerland) or equivalent. (f)  Centrifuge .—Centrifugal force higher than 2879 ×  g (Z320; B. HermLe AG, Gosheim, Germany), or equivalent. (g)  Nitrogen evaporator .—EVAP 112 (Organomation Associates, Inc., New Berlin, MA), or equivalent. (h)  TurboVap .—LV Evaporation System (Caliper Life Sciences, Hopkinton, MA), or equivalent. speed higher

(i)  Visiprep 5-port flask vacuum manifold .—RS-SUPELCO 57101-U (Sigma-Aldrich Shanghai Trading Co., Ltd). See Figure 2014.09A . (j)  Variable volume pipets .—10 μL, 200 μL, and 1 mL. (k)  Balance .—Capable of accurately measuring weights from 0.05 to 100 g within ±0.01 g. F. Extraction and Cleanup Procedure (a) Sample extraction.— ( 1 ) Weigh 5 g dry tea powder (accurate to 0.01 g) into an 80 mL centrifuge tube. ( 2 ) Add 15 mL acetonitrile. ( 3 ) Homogenize at 13500 rpm for 1 min.

Table 2014.09C. GC/MS/MS retention times, monitored ion transitions, collision energies, LODs, and LOQs for the 20 pesticides

Quantifying precursor/ production transition, m / z

Qualifying precursor/production transition, m / z

Retention time, min

Collision energy, V

No.

Pesticide

LOQ, μg/kg LOD, μg/kg

ISTD Heptachlor-epoxide

22.15 15.41 17.40 17.42 18.91 19.02 19.73 19.83 19.87 20.36 22.79 23.16 23.90 24.70 24.75 27.18 27.37 27.66 28.63 28.73 29.46

353/263 306/264 177/127 200/199 173/145 238/166 230/154 287/272 267/252 290/233 318/248 359/303 318/248 283/96 335/173 237/208 408/59 148/105 181/166 266/218 341/185

353/282 306/206 177/101 183/102 173/109 238/96 230/111 287/242 267/93 290/125 318/246 359/331 318/246 283/255 335/303 237/182 408/363 148/79 181/165 266/246 341/183

17;17 12;15 13;25 10;30 15;25 15;25

1 2 3 4 5 6 7 8 9

Trifluralin Tefluthrin

4.8 0.8 6.0 1.0 4.0 2.0

2.4 0.4 3.0 0.5 2.0 1.0 8.0 5.0 5.0 3.0 5.0 2.0 1.0 5.0

Pyrimethanil Propyzamide

Pirimicarb

Dimethenamid Fenchlorphos Tolclofos-methyl Pirimiphos-methyl

8;25

15;25 15;25

16.0 10.0 10.0

5;15

10 11 12 13 14 15 16 17 18 19 20

2,4’-DDE

15;15 10;10 25;25 10;10 10;10 25;25

6.0

Bromophos-ethyl

10.0

4,4’-DDE

4.0 2.0

Procymidone Picoxystrobin Quinoxyfen Chlorfenapyr

10.0 80.0

40.0 70.0

15;5

140.0

Benalaxyl Bifenthrin

15;25

2.0

1.0 5.0

10;5

10.0 20.0

Diflufenican

25;10 15;15

10.0

Bromopropylate

8.0

4.0