This document details a method for identifying and quantitating pesticide residues in food matrices, specifically chamomile and ginger extracts. It focuses on the use of triggered Multiple Reaction Monitoring (tMRM) acquisition on an Agilent 6460 Triple Quadrupole LC/MS system coupled with an Agilent 1290 LC system. The method addresses challenges in multiresidue analysis where endogenous matrix compounds can cause false positive identifications.
The note presents two specific case studies: the analysis of tebuthiuron in chamomile and tebufenpyrad in ginger. In both instances, endogenous compounds in the samples shared similar mass-to-charge ratios and retention times with the target pesticides, leading to potential false positives in conventional MRM analysis. The application demonstrates how tMRM acquisition, combined with library matching and strict retention time/ion ratio criteria, successfully differentiates these endogenous interferences from actual pesticide contamination, providing unambiguous identification and reliable quantitative data.
| LC column | ZORBAX Eclipse Plus C-18 RRHD column 100 x 2.1 mm, 1.8 pm |
|---|---|
| Flowrate | 0.500 mL/min |
| Injection volume | 2 ul |
| API drying gas | 7 L/min @ 200 °C |
| Sheath gas | 12 L/min @ 375 °C |
| Total number of MRMs | 390 |
| Maximum number of concurrent MRMs | 84 |
| Minimum dwell time | 3.64 ms |
The analysis is performed using an Agilent 1290 LC system coupled to an Agilent 6460 Triple Quadrupole LC/MS with tMRM acquisition.
In this application note, 51 pesticides were analyzed using tMRM acquisition.
The retention time of the analytes must not vary beyond 2.5 %.