Evaluation of different solid-phase traps for automated collection and clean-up in the analysis of multiple pesticides in fruits and vegetables after supercritical fluid extraction.

This study was designed to determine which combination of sorbent-trap and elution solvent provided the most efficient automated method of collection in supercritical fluid extraction (SFE), elution of analytes, and clean-up of orange, sweet potato and green bean extracts for analysis of 56 diverse pesticides using GC-ion-trap MS. The solid-phase traps evaluated consisted of octyldecylsilane (ODS), diol, Tenax and Porapak-Q, and the elution solvents compared were acetone, ethyl acetate, acetonitrile and methanol. SFE collection by bubbling into each organic solvent was also compared. Recoveries, elution volumes, limits of detection and clean-up aspects were determined for each combination of commodity, trap and solvent tested. High trapping efficiencies were achieved in each case, and acetone usually eluted the pesticides in the least volume (< 1 ml) from the traps. The few matrix components that interfered in GC-ion-trap MS continued to interfere in all trap/solvent pairs, and limits of detection were independent of trap/solvent combination. The use of the ODS trap and acetone elution solvent gave the most consistently high recoveries of the traps and solvents tested.