Applications of LC/ESI-MS/MS and UHPLC/Qq-TOF-MS for the determination of 141 pesticides in tea.
This paper presents the applications of LC-electrospray ionization (ESI)/MS/MS and ultra-HPLC (UHPLC)/ESI quadrupole (Qq)-time-of-flight (TOF) MS for the determination of 141 pesticides in tea. Pesticides were extracted and cleaned up from tea with a modified quick, easy, cheap, effective, rugged, and safe method using graphitized carbon black and primary-secondary amine sorbents. Quantification was achieved using matrix-matched standard calibration curves with isotopically labeled standards or a chemical analog as internal standards in an analytical range from 5 to 500 microg/kg. The LC/ESI-MS/MS served as a reliable tool to quantify the pesticides due to its superior sensitivity and good repeatability. Its method performance characteristics that include overall recovery, intermediate precision, and measurement uncertainty were evaluated according to a statistically designed experiment, i.e., a nested design. About 87% of the pesticides had recoveries between 81 and 110%; 94% had an intermediate precision < or = 20%; and 90% showed measurement uncertainty < or = 40%. About 92% of the pesticides were able to be detected at 5 microg/kg with an S/N > or = 3. The UHPLC/Qq-TOF-MS showed much less sensitivity and poorer repeatability compared to the LC/ESI-MS/MS, and, therefore, it was primarily used for confirmatory purposes based on the accurate mass measurement and isotopic patterns.
Canadian Food Inspection Agency, Calgary Laboratory, 3650-36th St NW, Calgary, Alberta, Canada T2L 2L1. Jian.Wang@inspection.gc.ca
Jian
J
Wang
Willis
W
Chow
Daniel
D
Leung
D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation / Q000379:methods*; D005506:Food Contamination / Q000032:analysis; D010573:Pesticide Residues / Q000032:analysis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000295:instrumentation / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000295:instrumentation / Q000379:methods*; D013662:Tea / Q000737:chemistry*
D010573:Pesticide Residues; D013662:Tea