Supercritical fluid extraction of organophosphorus pesticides from orange samples: Effect of solid additives on recovery

A method based on extraction with supercritical carbon dioxide has been developed for the analysis of pesticides in fruit. The method was tested on ten organophosphorus pesticides and dicloran in orange samples. Various solid additives including anhydrous sodium sulfate, Extrelut and diatomaceous earth were examined as extraction enhancers. Also tested were magnesium silicate as interference adsorbent, to increase selectivity, and sodium carbonate as alkaline salt, to prevent acidification of the sample by CO2. The recoveries obtained by SFE (92-104 %; mean relative standard deviation 10 %) were higher than those of conventional methods. The polar pesticide methamidophos, however, was not recovered.