The estimation of residue levels of promacyl and its metabolites in beef tissue and fat by high‐performance liquid chromatography with electrochemical detection

Abstract

A method is described for the estimation of residues of the carbamate insecticide promacyl [5‐methyl‐m‐cumenyl butyryl(methyl)carbamate] and its metabolites that are hydrolysable to isothymol (m‐cymen‐5‐ol), using high‐performance liquid chromatography with electrochemical detection to determine the isothymol. Clean‐up of samples relied on the steam volatility of phenols. Recoveries at the 0.1 mg kg−1 level varied from 72–88% for fat tissue and 81–91% for liver. The limits of detection were found to be 0.01 mg kg−1 for and 0.02 mg kg−1 for liver. A comparative study of the chromatography of sample extracts using both ultraviolet detection and electrochemical detection showed a substantial decrease in the level of interfering co‐eluates in the latter method. A field trial, involving a single spray application of the formulated acaricide on milking cattle, revealed residues in the butter fat comparable with those found in a previous investigation.