FEASIBILITY OF THIOCARBAMATE PESTICIDE ANALYSIS IN APPLES BY SUPERCRITICAL-FLUID EXTRACTION AND HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

Supercritical fluid extraction produced comparable results with liquid-solid extraction for the analysis of several thiocarbamate pesticides from apples at the 2 ppm spike level. These results were achieved with a simple one-step extraction procedure. The use of diatomaceous earth (Celite, Supelco, Inc.; Bellefonte, PA) served to increase thiocarbamate recoveries by aiding in the immobilization of the aqueous component of the apple matrix. High-performance liquid chromatography coupled with ultraviolet absorbance detection (HPLC-UV) had the most viable means of quantitation when compared with micro-HPLC-sulfur chemiluminescence detection (SCD) and gas chromatography-flame-ionization detection (GC-FID). The small injection volumes used with the micro-HPLC-SCD system made thiocarbamate detection at a spiking level of 2 ppm impossible. SCD did provide, however, valuable qualitative information about the nature of the apple coextractants. © Oxford University Press 1993.