AOAC Final Action Methods in 2018

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

ionization source and Model G1367D autosampler with a Mass Hunter data processing software system (Agilent Technologies). ( 2 )  Column .—Zorbax SB-C18, 2.1 × 100 mm × 3.5 μm, or equivalent. ( 3 )  Mobile phase gradient elution program and flow rate .— See Table 2014.09E . ( 4 )  Column temperature .—40°C.

( 2 ) Operating conditions are the same as for GC-MS with the exception that the ion monitoring mode is by selected reaction monitoring (SRM) and monitoring one precursor ion and two product ion transitions. ( 3 ) The monitored ion transitions and the collision energies for the 20 pesticides of interest in the study and heptachlor epoxide are shown in Table 2014.09C . The SRM acquisition parameters for the precursor and product ion transitions monitored by GC-MS/MS are shown in Table 2014.09D . (c) LC-MS/MS analysis.— ( 1 )  LC-MS/MS system .—An Agilent Series 1200 HPLC system directly coupled to a 6430 triple quadrupole mass spectrometer equipped with an electrospray

( 5 )  Injection volume .—10 μL. ( 6 )  Ionization mode .—ESI. ( 7 )  Ion source polarity .—Positive ion. ( 8 )  Nebulizer gas .—Nitrogen gas. ( 9 )  Nebulizer gas pressure .—0.28 Mpa.

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

© 2018 AOAC INTERNATIONAL