Reduced Recovery of Dieldrin Residues—A Shortcoming of Sulfuric Acid Cleanup of Biological Samples

Abstract
Reduced quantitative recovery of dieldrin (1,2,3,4,10,10-hexachloro-6,7-epoxy-1,4,4a,5,6,7,8,8a-octahydro-1,4-endo, exo-5,8-dimethanonaphthalene) while using concentrated sulfuric acid for the cleanup of the extracted samples, has been investigated by gas-liquid chromatography and infrared (IR) spectroscopy. In vitro studies have shown that the servere breakdown in the recovery of dieldrin can be checked if 65% (v/v) H2SO4 is used as opposed to the concentrated H2SO4. Infrared studies revealed that at concentrations > 70% sulfuric acid, the epoxide ring attached to the norbornene nucleus of dieldrin undergoes rearrangement to form keto-dihydroaldrin.