Development of Enhanced Analytical Methodology in Pesticide Chemistry

University dissertation from Uppsala : Acta Universitatis Upsaliensis

Abstract: The analysis of pesticide residues in fruit, vegetables, rape seed and water has been improved using developments in sample handling and analytical techniques. The method development is associated with analytical difficulties, since pesticides currently used in agriculture represent a variety of chemical classes having very different physico chemical properties. The method development also encounters difficulties when many various commodity classes with different characteristics are studied. The main task in pesticide residue analysis has been to provide multi residue methods, and traditionally GC has been the main analytical technique.In order to regulate the use of hazardous pesticides, the EU commission introduces strict maximum residue levels (MRL). The need for improved sample handling and detection techniques are, however, high due to handling of lower detection limits, complex matrices and the need of more efficient sample throughput. Of the new techniques introduced as alternative techniques to the traditional extraction techniques, pressurised fluid extraction (PFE) has shown to be a promising technique in analysis of pesticide residues in fatty foodstuffs.In water analysis, large sample volumes are needed due to low MRLs. The solid phase extraction (SPE) technique allows a concentration of large sample volumes and simplifies the tedious laboratory work with traditional separation funnels. A new approach was to use non-polar solvents for the sample extraction from the earlier used polymeric column. Both these techniques provide low solvent consumption, short extraction times and ability to automate the manual steps. An LC-MS/MS multi residue method was finally developed for pesticide residues in fruit and vegetables. The technique is robust and sensitive and allows a simultaneous determination of 57 pesticides and metabolites in one single analysis and without any clean-up steps. The sensitivity was improved to achieve the maximum residue limits needed by EU. Several multi step methods, which involve more costly analysis, has been replaced by this technique.

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