2. AOACRIChemContMethods-2018Awards

1436 Pang et al.: J ournal of AOAC I nternational V ol. 98, N o. 5, 2015

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

Qualifying precursor/ product ion transition, m / z

Retention time, min

Collision energy, V Fragmentation, V LOQ, μg/kg LOD, μg/kg

No.

Pesticide

ISTD Chlorpyrifosmethyl

16.01

322.0/125.0

322.0/290.0

15; 15 10; 10

80 80 80

1 2 3 4 5 6 7 8 9

Imidacloprid

3.81 5.89 6.83

256.1/ 209.1 256.1/175.1

22.0 24.4

11.0 12.2

Propoxur

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

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

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

( 2 ) Measure the ion abundances for the qualifier ions for the detected pesticides and verify that they are within the expected limits. If the peaks match, the presence of the pesticide is confirmed. See Table 2014.09H . (b) Quantitative calculations.— ( 1 ) Use instrument data processing software for GC/MS (SIM), GCMS/MS, and/or LC/MS/MS to calculate a response ratio (measured abundance of pesticide/measured abundance of heptachlor epoxide for GC and chlorpyrifos methyl for LC) and construct a five-point matrix-matched calibration curve of response ratio versus concentration of pesticide in standard solution. ( 2 ) Using the regression data from the appropriate matrix- matched calibration curve, calculate the concentration of each pesticide found in the samples. ( 3 ) If a validated computer system is not being used for calculations, follow the steps below:

( a ) Measure the peak area of each respective standard level for each pesticide and the peak area of corresponding ISTD. ( b ) Calculate the ratio of the analyte response to that of the ISTD. ( c ) Run a linear regression analysis using the ratio of each pesticide at five different levels with no weighting or 1/x weighting, where x = concentration. ( d ) Measure the peak area of each pesticide found in the sample and the peak area of corresponding ISTD. ( e ) Calculate the amount of each pesticide in the solution injected from the standard curve. ( f ) Calculate the amount of each pesticide present in the sample. Test results should be reported to two decimal places or four significant digits.

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