Quantitative Analysis Of Pesticides In Quechers Extracts Using UPLC- and APGC- MS/MS
Poster May 05, 2015
Sara Stead, Simon Hird, Eimear McCall
Pesticides are widely used in the production of fruit and vegetables across the globe. Governments, food producers and food retailers have a duty to ensure they are not present in final products for consumption. Most countries have regulations governing pesticide residues in food. For pesticides in food products, legislation imposes Maximum Residue Limits (MRLs) which lead to the requirement for analytical techniques that are sensitive, selective and reproducible. Multi-residue pesticide analysis is challenging due to the low limits of detection required in a diverse range of food commodities. As there are currently in excess of 1000 pesticides in use, laboratories are under increasing pressure to broaden the range of pesticides determined in ever shorter turnaround times. The renowned QuEChERS extraction method has been pivotal in this approach, however different chromatographic techniques are typically required for the efficient detection of the multitude of pesticide residues; either by gas chromatography or liquid chromatography, typically coupled with tandem mass spectrometer systems.
Typically, GC analysis is carried out using a dedicated GC-MS/MS system with an EI source. As shown by Portoles et al,  EI causes extensive fragmentation of some pesticides leading to poor sensitivity and selectivity, as demonstrated in Figure 1. APGC is a soft ionisation technique which generates high relative and absolute abundance molecular ions resulting in highly sensitive and selective MRM transitions. Furthermore, the APGC source is interchangeable with the LC electrospray source enabling a single MS instrument to be used for the analysis of both LC and GC amenable pesticides [Figure 2]. In this study, we demonstrate sensitive, accurate and repeatable results for the analysis of pesticides in QuEChERS extracts of a selection of
commodities below the regulatory limits.
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The Use of Pyrolysis/GCMS and Newly Developed Libraries to assist in Characterizing Complex Polymeric SamplesPoster
Pyrolysis-GC/MS is an effective tool in introducing and analyzing polymers. But since the polymer must be broken down to volatile segments in order to be sent to the GC, identification by the Mass Spec does not look at the original polymer, but only the fragments. This poster will look at a unique library designed to work with the existing NIST library, however contains averaged spectra of pyrolyzed polymers so it can be used to directly identify the original polymer sample.READ MORE