Confirmation of a Carboxylic Acid Metabolite of Polychlorotrifluoroethylene and a Method for Its GC-ECD Analysis in Biological Matrices

Abstract

3.1 Oil, referred to as polychlorotrifluoroethylene (pCTFE), is a polymeric mixture consisting primarily of trimers and tetramers of chlorotrifluoroethylene (CTFE) end-capped with chlorine. Inhalation studies have associated dose-related body weight loss, increased organ weights, and abnormal hepatic enzyme activities with exposure to pCTFE. The carboxylic acid metabolites of pCTFE have been shown to cause hepatotoxicity in rats, which is manifested by increased liver weights and the proliferation of hepatic peroxisomes. A method was developed to derivatize these carboxylic acid metabolites. Tissue homogenates and feces were extracted with methanol, and urinary metabolites were extracted on octadecylsilane (ODS) solid-phase extraction columns. Aliquots of the extracts and whole blood were methylated with 3N methanolic HCI to transesterify the carboxylic acid metabolites to volatile methyl esters. The pCTFE methyl esters were analyzed by gas chromatography (GC) with electron capture detection (ECD). The on-column limit of detection was 5 pg for each methyl ester. Solid-phase extraction of spiked urine gave extraction efficiencies of 90.4% for the trimer acid and 84.7% for the tetramer acid. This method was successfully applied to toxicity studies in rats and nonhuman primates. The identities of the derivatized metabolites were confirmed by GC/MS.