AOAC Final Action Methods in 2018

Table 2014.09F. LC-MS/MS retention times, ion transitions, collision energies, LODs, and LOQs for the 20 pesticides of interest in this study

Quantifying precursor/ production transition, m / z 322.0/125.0 256.1/ 209.1 210.1/111.0 215.1/126.0 240.1/125.0 243.1/173.0 294.2/69.0 270.2/224.0 324.2/262.1 326.2/148.1 314.1/267 368.1/145.0 306.2/164.0 305.0/169.1 398.0/158.1 308.0/197.0 334.3/147.0 528.0/150.0 409.3/186.1 350.0/198.0 296.1/240.1

Qualifying precursor/ product ion transition, m / z 322.0/290.0 256.1/175.1 210.1/168.1 215.1/148.1 240.1/89.1 243.1/215.0 294.2/197.1 270.2/148.2 324.2/282.1 326.2/294.0 314.1/206.0 368.1/205.0 306.2/108.1 305.0/153.2 398.0/314.0 308.0/272.0 334.3/117.1 528.0/218.0 409.3/206.2 350.0/97.0 296.1/222.1

Collision energy, V Fragmentation, V

Retention time, min

No.

Pesticide

LOQ, μg/kg LOD, μg/kg

ISTD Chlorpyrifosmethyl

16.01

15; 15 10; 10

80 80 80

1 2 3 4 5 6 7 8 9

Imidacloprid

3.81 5.89 6.83

22.0 24.4

11.0 12.2

Propoxur

10; 5

Monolinuron Clomazone Ethoprophos Triadimefon Acetochlor

15; 10 20; 50 10; 10 20; 15

100 100 120 100

3.6 0.4 2.8 7.9

1.8 0.2 1.4 3.9

8.3

11.37 11.64 12.94 13.25 14.40 14.58 14.99 15.05 15.20 15, 45 16.60 16.82 16.76 16.82 17.65 17.98

5; 20

80

47.4

23.7

Flutolanil Benalaxyl

20; 10

120 120

1.1 1.2

0.6 0.6

15; 5

10 11 12 13 14 15 16 17 18 19 20

Kresoxim-methyl

5; 5

80 80

100.6

50.3

Picoxystrobin

20; 5

8.4 0.2 0.7

4.2 0.1 0.4

Pirimiphos-methyl

20; 30 20; 20

120 160

Diazinon Bensulide Quinoxyfen Tebufenpyrad

20; 5

80

34.2

17.1 76.7

35; 35 25; 40 20; 20 15; 10 20; 35 10; 20

180 160 120 120 100 100

153.4

0.3 7.5 2.0

0.1 3.8 1.0

Indoxacarb

Trifloxystrobin Chlorpyrifos

53.8

26.9

Butralin

1.9

1.0

( 3 ) Load the rinse into the cartridge when the level of the loading solution in the cartridge reaches the top of the anhydrous sodium sulfate packing. ( 4 ) Connect a 30 mL reservoir onto the upper part of the cartridge using an adapter ( see Figure 2014.09 ). ( 5 ) Elute the cartridge with 25 mL acetonitrile–toluene (3 + 1, v/v). ( 6 ) Evaporate the eluate to approximately 0.5 mL using a rotary evaporator (or TurboVap) in a 40°C water bath. For GC-MS and/or GC-MS/MS analysis only: ( 7 ) Add 40 μL heptachlor epoxide (internal standard; ISTD) working standard solution to the sample in F ( b )( 6 ). ( 8 ) Evaporate to dryness under a stream of nitrogen in a 35°C water bath (or Turbo Vap).

( 9 ) Dissolve the dried residue in 1.5 mL hexane, ultrasonicate the samples to mix, and filter through a 0.2 μm membrane filter. The sample is ready for GC-MS or GC-MS/MS analysis. For LC-MS/MS analysis only: ( 10 ) Add 40 μL chlorpyrifos methyl (ISTD) working standard solution to the sample prepared in F ( b )( 6 ). ( 11 ) Evaporate to dryness under a stream of nitrogen in a 35°C water bath (or Turbo Vap). ( 12 ) Dissolve the dried residue in 1.5 mL acetonitrile–water (3 + 2, v/v), ultrasonicate the samples to mix, and filter through a 0.2 μm membrane filter. The sample is ready for LC-MS/MS analysis. G. Quantitative Analysis (a) Criteria for identification and confirmation .—( 1 ) Measure the retention time of the monitored peaks and match them with the same peaks in the pesticide standard chromatograms.

Table 2014.09G. SRM acquisition parameters by LC-MS/MS analysis for the 20 pesticides Group Start time, min Monitored ion transitions, m / z

Dwell time, ms

1

0

256.1/209.1, 256.1/175.1, 210.1/111.0, 210.1/168.1, 240.1/125.0, 240.1/89.1, 243.1/173.0, 243.1/215.0, 294.2/69.0, 294.2/197.1, 215.1/126.0, 215.1/148.1 270.2/224.0, 270.2/148.2, 306.2/164.0, 306.2/108.1, 324.2/262.1, 324.2/282.1, 326.2/148.1, 326.2/294.0, 305.0/169.1, 305.0/153.2, 314.1/267.0, 314.1/206.0, 322.0/125.0, 322.0/290.0, 368.1/145.0, 368.1/205.0, 398.0/158.1, 398.0/314.0 334.3/147.0, 334.3/117.1,528.0/150.0,528.0/218.0, 409.3/186.1, 409.3/206.2,296.1/240.1, 296.1/222.1, 350.0/198, 350.0/97.0, 308.0/197.0, 308.0/272.0

30

2

12

20

3

16.4

25

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