Miniaturisation and optimisation of the Dutch mini-Luke extraction method for implementation in the routine multi-residue analysis of pesticides in fruits and vegetables.

This paper presents the validation and further miniaturisation of the well-known Dutch mini-Luke method for high water and acid content matrices for 175 pesticides amenable to liquid- and gas chromatography-mass spectrometry. For optimisation of the method, recovery tests with different sample/extraction solvent ratios, varying amounts of dichloromethane and salts were performed with fifty representative pesticides. Solvent consumption could be reduced considerably, especially for the dichloromethane (by a factor of 3).

A multi-residue method for pesticides analysis in green coffee beans using gas chromatography-negative chemical ionization mass spectrometry in selective ion monitoring mode.

In this study, a new gas chromatography-mass spectrometry (GC-MS) method, using the very selective negative chemical ionization (NCI) mode, was developed and applied in combination with a modified acetonitrile-based extraction method (QuEChERS) for the analysis of a large number of pesticide residues (51 pesticides, including isomers and degradation products) in green coffee beans. A previously developed integrated sample homogenization and extraction method for both pesticides and mycotoxins analysis was used. An homogeneous slurry of green milled coffee beans and water (ratio 1:4, w/w) was prepared and extracted with acetonitrile/acetic acid (1%), followed by magnesium sulfate addition for phase separation.