False Positives and False Negatives for Specific Problematic Compounds European Union Reference Laboratory - FV

European Union Reference Laboratory - FV

Solutions for addressing specific LC-MS problematic pesticide residues in multiresidue methods. Part I

Online videotutorial

Francisco José Díaz-Galiano Amadeo R. Fernández-Alba European Union Reference Laboratory - FV

Problems related to reporting false positives and false negatives for specific problematic compounds European Union Reference Laboratory - FV

False positives and false negatives EUPT SC03 (avocado) 7 laboratories reported 8 false positives

RL Concentration Determination Code Pesticide (mg/kg) (mg/kg) technique

Lab047 Azinphos-methyl 0.01 0.133732643 LC-QQQ-MS/MS

Lab012 Etofenprox 0.01 0.0878 LC-QQQ-MS/MS

Formetanate (expressed as Lab032 0.01 0.241 LC-QQQ-MS/MS formetanate (hydrochloride)) Prothioconazole Lab047 False negative for Phosmet Lab007 (Prothioconazole-desthio) (sum of 0.01 0.21 LC-Orbitrap-MS isomers) LC-QQQ-MS/MS Lab062 Tebuconazole 0.01 0.02 GC-QQQ-MS/MS European Union Reference Laboratory - FV

False positives and false negatives EUPT SC03 (avocado) Azinphos-methyl

Phosmet (SC03 sample)

Azinphos-methyl acquisition window (SC03 sample) European Union Reference Laboratory - FV

False positives and false negatives EUPT SC03 (avocado) 7 laboratories reported 8 false positives

RL Concentration Determination Code Pesticide (mg/kg) (mg/kg) technique

Lab047 Azinphos-methyl 0.01 0.133732643 LC-QQQ-MS/MS

Lab012 Etofenprox 0.01 0.0878 LC-QQQ-MS/MS

Formetanate (expressed as Lab032 0.01 0.241 LC-QQQ-MS/MS formetanate (hydrochloride)) Prothioconazole Lab007 (Prothioconazole-desthio) (sum of 0.01 0.21 LC-Orbitrap-MS isomers) LC-QQQ-MS/MS Lab062 Tebuconazole 0.01 0.02 GC-QQQ-MS/MS European Union Reference Laboratory - FV

False positives and false negatives EUPT SC03 (avocado) Etofenprox

Std. etofenprox in avocado 0.500 mg/L

EUPT-SC03 sample European Union Reference Laboratory - FV

False positives and false negatives EUPT SC03 (avocado)

SC03 Sample 0.010 mg/L

0.050 mg/L 0.100 mg/L

0.250 mg/L 0.500 mg/L European Union Reference Laboratory - FV

False positives and false negatives EUPT SC03 (avocado)

0.0500.2500.0100.5000.100 mg/L European Union Reference Laboratory - FV

False positives and false negatives EUPT SC03 (avocado) 7 laboratories reported 8 false positives

RL Concentration Determination Code Pesticide (mg/kg) (mg/kg) technique

Lab047 Azinphos-methyl 0.01 0.133732643 LC-QQQ-MS/MS

Lab012 Etofenprox 0.01 0.0878 LC-QQQ-MS/MS

False positives and false negatives EUPT SC03 (avocado)

376.0 -> 308.0 , 376.0 -> 266.0

ts x10 5 Ratio = 13.1 (101.1 %) oun C 1.8

1.6 1.4 Prochloraz in SC03 sample 1.2

1 (Prochloraz’s acquisition 0.8 window) 0.6

0.4

0.2

12 12.1 12.2 12.3 12.4 12.5 12.6 12.7 Acquisition Time (min)

308.0 -> 70.0 , 308.0 -> 125.0

ts x10 4 Ratio = 0.1 (2.5 %) oun

C 1.3 1.2 1.1 1 0.9 Prochloraz in SC03 sample 0.8 0.7 (Tebuconazole’s acquisition 0.6 0.5 window) 0.4 0.3 0.2 0.1 0 -0.1 12 12.1 12.2 12.3 12.4 12.5 12.6 12.7 Acquisition Time (min) European Union Reference Laboratory - FV

False positives and false negatives EUPT SC03 (avocado) Prochloraz (Prochloraz’s acquisition window)

Tebuconazole Prochloraz (Tebuconazole’s acquisition window) (Tebuconazole’s acquisition window) European Union Reference Laboratory - FV

Tentative false positives and negatives: common mass transitions

352 > 200 O 352 > 125 367 > 350 O 367 > 125 O N 350 > 125 Fenpropathrin Exact mass: 349.1678 Da 350 > 97

350 > 198 350 > 125 350 > 97 Depending on the selected mass transitions in LC-QqQ-MS/MS, false positives or negatives might be reported for chlorpyriphos and fenpropathrin European Union Reference Laboratory - FV

Tentative false positives and negatives: common mass transitions

331.0 -> 127.0 , 331.0 -> 204.8 331.0 -> 127.0 , 331.0 -> 204.8 331.0 -> 127.0 , 331.0 -> 204.8 5 x10 4 x10 Ratio = 16.5 (113.0 %) Coelution Score = 99.8 x10 5 Ratio = 14.6 (100.0 %) Coelution Score = 99.6 Not Found 0.9 Counts

Counts 0.9 Counts 8 0.8 0.8 7 0.7 0.7 6 Cl 0.6 0.6 5 0.5 0.5

0.4 0.4 4

0.3 0.3 3

Cl O 0.2 0.2 2 (Z) O H P 0.1 0.1 1 O O 0 0 0 Cl 10.9 11 11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8 11.9 12 10.9 11 11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8 11.9 12 10.9 11 11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8 11.9 12 Dimethylvinphos (Z isomer) Acquisition Time (min) Acquisition Time (min) Acquisition Time (min) Chemical Formula: C10H10Cl3O4P Dimethylvinphos Dimethylvinphos & Malathion Malathion Exact Mass: 329.9382 Molecular Weight: 331.5098 Dimethylvinphos monitored MRM transitions Dimethylvinphos monitored MRM transitions Dimethylvinphos monitored MRM transitions 331 > 127 Hint: make use of the several chlorine atoms in Malathion Malathion & Dimethylvinphos Dimethylvinphos dimethylvinphos to select a Malathion monitored MRM transitions Malathion monitored MRM transitions Malathion monitored MRM transitions

different precursor ion (333) 331.0 -> 127.1 , 331.0 -> 285.0 331.0 -> 127.1 , 331.0 -> 285.0 331.0 -> 127.1 , 331.0 -> 285.0 x10 4 Ratio = 32.9 (100.0 %) Coelution Score = 99.9 x10 5 Ratio = 28.9 (116.2 %) Coelution Score = 99.4 x10 5 Ratio = 0.0 (0.0 %) Coelution Score = 8.1 0.9 0.9 Counts Counts O Counts 8 0.8 0.8 7 O O 0.7 0.7 O O P 6 0.6 0.6 S S 5 0.5 0.5 O 4 0.4 0.4 Malathion 3 0.3 0.3 2 0.2 0.2 Chemical Formula: C10H19O6PS2 1 0.1 0.1 Exact Mass: 330.0361 0 0 0 Molecular Weight: 330.3498 10.8 10.9 11 11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8 10.7 10.8 10.9 11 11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8 10.7 10.8 10.9 11 11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8 Acquisition Time (min) Acquisition Time (min) Acquisition Time (min) European Union Reference Laboratory - FV

Tentative false positives and negatives: common mass transitions

Terbutylazine Terbutylazine & Propazine Propazine Terbutylazine monitored MRM transitions Terbutylazine monitored MRM transitions Terbutylazine monitored MRM transitions

CH3 N N Propazine Propazine & Terbutylazine Terbutylazine N N N H H Propazine monitored MRM transitions Propazine monitored MRM transitions Propazine monitored MRM transitions

Propazine

230 > 146 European Union Reference Laboratory - FV

Tentative false positives and negatives: common mass transitions 239.9 -> 223.0 , 239.9 -> 86.0 x10 4 Ratio = 20.3 (96.9 %) Coelution Score = 99.9 239.9 -> 223.0 , 239.9 -> 86.0 239.9 -> 223.0 , 239.9 -> 86.0 4 4 2.6 x10 Ratio = 46.8 (100.0 %) Coelution Score = 99.6 x10 Ratio = Coelution Score = 99.9 Counts 6 3

2.4 Counts Counts 2.8 5.5 2.2 2.6 2 5 2.4 1.8 4.5 2.2 1.6 4 2 1.4 3.5 1.8 1.6 1.2 3 1.4 1 2.5 1.2 0.8 2 1 0.6 1.5 0.8 0.6 0.4 1 0.4 0.2 0.5 0.2 0 0 0 -0.2 -0.5 -0.2 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 O H C Acquisition Time (min) Acquisition Time (min) Acquisition Time (min) 3 O N N O S Aldicarb-sulfone Aldicarb-sulfone & Butoxycarboxim Butoxycarboxim H O Aldicarb-sulfone monitored MRM transitions Aldicarb-sulfone monitored MRM transitions Aldicarb-sulfone monitored MRM transitions Aldicarb-sulfone

O O N N O S Butoxycarboxim Butoxycarboxim & Aldicarb-sulfone Aldicarb-sulfone H O H3C Butoxycarboxim monitored MRM transitions Butoxycarboxim monitored MRM transitions Butoxycarboxim monitored MRM transitions Butoxycarboxim 240.1 -> 222.7 , 240.1 -> 165.9 240.1 -> 222.7 , 240.1 -> 165.9 240.1 -> 222.7 , 240.1 -> 165.9 4 x10 Ratio = 31.7 (100.0 %) Coelution Score = 100.0 x10 4 Ratio = 34.8 (110.0 %) Coelution Score = 100.0 x10 4 Ratio = 25.9 (91.7 %) Coelution Score = 99.9 3.25 3 Counts Counts Counts 6 3 2.8 5.5 2.75 2.6 5 2.4 2.5 2.2 2.25 4.5 2 4 240 > 223 2 1.8 3.5 1.75 1.6 1.5 3 1.4 1.25 2.5 1.2 240 > 86 1 2 1 0.8 0.75 1.5 0.6 0.5 1 0.4 240 > 166 0.25 0.5 0.2 0 0 0 -0.25 -0.5 -0.2 2.9 3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 2.9 3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 2.9 3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 Acquisition Time (min) Acquisition Time (min) Acquisition Time (min) European Union Reference Laboratory - FV

Summary and key points European Union Reference Laboratory - FV

Coextracted matrix interferences (avocado) found within EUPTs

394.2 > 177.3 Very different ion 394.2 > 359.1 ratio in the avocado 394.2 > 107.1 coextracted matrix component European Union Reference Laboratory - FV

Compounds with common mass transitions found within EUPTs

O S P N SO O O Phosmet Chemical Formula: C11H12NO4PS2 Exact Mass: 316.9945 Da Pay attention to the m/z: 316.9945 (100.0%), 317.9979 (11.9%), 318.9903 (4.5%), 318.9903 (4.5%) retention times and exclusive mass transitions

318.0 > 160.0 318.0 > 261.0 318.0 > 133.0 318.0 > 132.1 Elutes earlier Elutes later European Union Reference Laboratory - FV

Compounds with common mass transitions found within EUPTs

A prochloraz fragment can be fragmented again to give rise to the 308.0 > 70.0 mass transition

308.0 > 70.0 376.0 > 308.0 308.0 > 125.0 376.0 > 266.0 Elutes earlier Elutes later European Union Reference Laboratory - FV

Compounds with common mass transitions (other)

Avoid the 350 m/z precursor for chlorpyrifos

O 367 > 350 350 > 198 352 > 200 367 > 125 350 > 125 O 352 > 125 O 350 > 125 350 > 97 N Elutes earlier Fenpropathrin 350 > 97 Elutes earlier Exact mass: 349.1678 Da Elutes later European Union Reference Laboratory - FV

Compounds with common mass transitions (other) Cl

O O Cl O S O (Z) O H P O P O O S O Cl O Dimethylvinphos (Z isomer) Malathion Chemical Formula: C10H10Cl3O4P Chemical Formula: C10H19O6PS2 Exact Mass: 329.9382 Da Exact Mass: 330.0361 m/z: 329.9382 (100.0%), 331.9353 Employ the 333 m/z m/z: 330.0361 (100.0%), 331.0394 (95.9%), 333.9323 (30.6%), for dimethylvinphos (10.8%), 332.0319 (9.0%), 330.9416 (10.8%), 332.9386 (10.4%) 331.0355 (1.6%), 332.0403 (1.2%)

331.0 > 127.0 331.0 > 127.1 331.0 > 204.8 331.0 > 285.0 Elutes later Elutes earlier European Union Reference Laboratory - FV

Compounds with common mass transitions (other)

Pay attention to the retention times and exclusive mass transitions

230.0 > 174.0 230.0 > 146.0 230.0 > 146.0 230.0 > 187.9 Elutes later Elutes earlier European Union Reference Laboratory - FV

Compounds with common mass transitions (other)

O O N N O S H O Butoxycarboxim Pay attention to the Chemical Formula: C7H14N2O4S Exact Mass: 222.0674 Da retention times. m/z: 222.0674 (100.0%), 223.0708 (7.6%), 224.0632 (4.5%) Three mass transitions in common 239.9 > 223.0 240.1 > 222.7 239.9 > 86.0 240.1 > 165.9 Elutes later Elutes earlier European Union Reference Laboratory - FV

Thank you for your attention

This online tutorial is part of a series of online tutorials that will continue through the rest of the year: