The estimated pesticide use per hectare in 2012, in Costa Rica was 11.4 kg a.i for a total cultivated area of 773 819 ha [1]. The dithiocarbamate (DTC) mancozeb is the most widely used pesticide in the country due to its characteristics as a broad spectrum fungicide. Commonly, an acid digestion, transforming DTC in to carbon disulfide (CS2) methodology is used to analyze DTC residues. However, some crops belonging the Brassicaceae family (i.e. cabbage, broccoli and cauliflower) are known to inherently contain CS2 sources [2], what results in false positives.In this study a method was validated for the determination of DTCs in fruits and vegetables belonging to the Order brassicales, using acid digestion (HCl) and SnCl2 as the reducing agent, at 80 �C. DTCs were converted to CS2, absorbed in isooctane and subsequently detected by GC-MS/SIM. Three crops (cabbage, broccoli and papaya) of the brassicales order were used for the validation. For cabbage three concentration levels were used (0.5 , 3 and 5 mg/kg) , the recoveries were between 88 and 96 % with a relative standard deviation below 20 % and a good linearity ( r2>0.99).The method shows a good precision and accuracy, with less time needed per sample and using lower input of chemicals, compared to the traditional method.[1] SFE (Servicio Fitosanitario del Estado). Cifras de importaci�n, exportaci�n y aplicaci�n de plaguicidas en Costa Rica entre el 2008 y el 2012. Consultado el 08-03-2014 en: https://www.sfe.go.cr/agroquimicos/Cifras_de_plaguicidas_%202008_2012.pdf. Disponible en www.sfe.go.cr.[2] R.C. Perz, H. van Lishaut, W. Schwack, J. CS2 Blinds in Brassica Crops: False Positive Results in the Dithiocarbamate Residue Analysis by the Acid Digestion Method. Agric. Food Chem. 48 (2000) 792.

Validation of a GC-MS method for the determination of dithiocarbamate fungicide residues in brassicales

248th National Meeting (2014)

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