Determination of Captan, Folpet, and Captafol in Water, Apples, and Lettuce By Quantitative Thin-Layer Chromatography

Abstract

Captan, folpet, and captafol were determined in water, lettuce, and apples by TLC of extracts on preadsorbent silica gel layers, detection with silver nitrate reagent, and densitometric scanning. The fungicides were extracted from water on Chromosorb 102 raicrocolumns. Cleanup on a Florisil column was required for the food extracts. Recoveries from distilled and tap water ranged from 76–98% at 0.02 ppm and 81–94% at 0.007 ppm. Recoveries from lettuce ranged from 88–94% and from apples 84–90%, both at 0.25 ppm. The selectivity, sensitivity, and precision of the method are adequate for routine residue analysis.