The goal of this study was to develop and validate a simple high-throughput method for multi-class residual analysis of 174 pesticides, 14 environmental contaminants (PCBs), 64 veterinary drugs, plus 22 metabolites, in bovine muscle.  The choice of 274 targeted contaminants was based on the Brazilian National Plan for Control of Residues in Animal Products.  Sample preparation was the QuEChERS method, originally for veterinary drugs only, by extraction of 2 g sample with 10 mL of 4/1 (v/v) acetonitrile/water, which was extended to the other analytes.  A small portion of initial extract was diluted in water for analysis by ultrahigh-performance liquid chromatography - tandem mass spectrometry (UHPLC-MS/MS), and the remaining extract underwent salt-out partitioning with 1-2 g of 4/1 (w/w) MgSO<sub>4</sub> and NaCl. A 300 µL portion of the upper layer was cleaned-up by micro-solid phase extraction (µ-SPE) using an automated Instrument Top Sample Preparation (ITSP) system.  The final extracts were immediately injected after ITSP by low-pressure gas chromatography (LPGC-MS/MS) for analysis of pesticides and PCBs.  The UHPLC-MS/MS was also conducted in parallel for analysis of LC-amenable pesticides and veterinary drugs, with all methods taking &lt;15 min cycle times per sample.  For MS/MS on both instruments, 3 ion transitions were monitored to improve identification of the 274 targeted analytes at the known retention times and ion intensity ratios.  Isotopically-labeled internal standards for each class of contaminants and matrix-matched calibration standards were used to achieve accurate results with minimal matrix effects.  In LPGC-MS/MS, analyte protectants were added to all final extracts to mask active sites in the system and maintain instrument robustness.  Method validation of bovine muscle was conducted based on the Brazilian reference residue limits for each analyte.  The new method is expected to be implemented in Brazil and any other laboratory that wishes to streamline its residue monitoring program.

Innovative method for simultaneous determination of pesticides, veterinary drugs, and environmental contaminants residues in beef

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.