COMPARISON OF MULTIDIMENSIONAL APPROACHES (LC/MS-MS, GC/MS-MS AND GCxGC/MS) FOR THE ANALYSIS OF COMPLEX FOOD MATRICES

The screening strategies for the analysis of high sample dimensionality matrices (such as those found in foods) require the use of different multidimensional methods because of the wide variety of chemical properties to monitor. High-fat food matrices like milk, salmon, nuts, avocado, etc. can trap environmental toxicants that are of major concern for food regulatory agencies. Heat labile and low polarity compounds such as carbamates, neonicotinoids, and organophosphorilated pesticides are more amenable to LC-analysis, while non-polar pesticides such as organochlorinated compounds are better suited for GC-analysis. However, there are a significant number of compounds that can be screened by both techniques, and a general screening approach is thus needed to better ascertain the analysis of these samples. In this project we present the results of an investigation from the use of three different multidimensional approaches for the screening of a suite of 250 pesticides in high lipophilic samples using a modified QuEChERS extraction protocol. QuEChERS was used for the high-throughput, comprehensive extraction of pesticides from the food matrix, which was then followed by analysis by LC/MS-MS, GC/MS-MS and GC×GC/MS. Approximately 58% of the pesticides were amenable to LC/MS-MS analysis, with the remainder of the analytes more suitable for GC/MSMS. GC×GC/MS demonstrated its value as a general screening method in terms of its ability to extend the number of GC-amenable compounds that can be identified. 230 pesticides were found in the GC×GC/MS analyses, with detection limits of many of these compounds in the range of the more selective MS-MS technologies. Qualitative and quantitative validation considerations for the use of these technologies will also be presented.