Development and validation of an efficient automated method for the analysis of 300 pesticides in foods using two-dimensional liquid chromatography-tandem mass spectrometry

In this study, a fully automated system was developed for the determination of more than 300 different pesticides from various food commodities. The samples were extracted with acetonitrile prior to the injection into the two-dimensional LC-system. No manual clean-up was needed. The separation of analytes and matrix compounds was carried out by a YMC-Pack Diol (2.1 mm x 100 mm; 5 mu m; 120 angstrom) HILIC column in the first dimension. All analytes eluted within one small fraction at the beginning of the run. With a packed loop interface this fraction was transferred to the analytical reversed phase separation performed on an Agilent Poroshell 120 EC-C18 (2.1 mm x 100 mm; 2.7 mu m; 120 angstrom). Some very polar compounds with a stronger retention on the HILIC column were measured directly. The method was validated for over 300 pesticides in cucumber, lemon, wheat flour, rocket, and black tea. For the large majority of the analytes, the recovery was between 70% and 120% and the relative standard deviation was clearly under 20%. The limits of detection for nearly all the compounds were at least at 0.01 mg/kg. For over 50% of the analytes, good sensitivity was observed even at 0.001 mg/kg. In spite of the injection of a pure sample extract, the method showed robust results even with dirty matrices like hops and tea. (C) 2013 Elsevier B.V. All rights reserved.