Chromatographic purification and HPLC assay with electrochemicaldetection ofdiethylstilboestrol residues in meat

A rapid, reliable and sensitive procedure is reported for the detection of residues of total diethylstilboestrol (DES) (free and conjugated) in bovine muscle samples. Prior to analysis, the DES in the sample was enzymatically deconjugated. Subsequently the sample was subjected to a clean-up procedure using a two-trap system composed of a first cartridge of non-specific adsorbing material (C 18) and of a second cartridge containing a sulphonic acid type silica-based anion exchanger. The determination was performed by HPLC with electrochemical detection. Analytical variables such as efficiency of hydrolysis, enzyme purification, hydrodynamic voltammetric studies and variation in the DES trans/cis ratio were investigated. Mean recovery of total DES was 87.3%. The precision of the procedure was 7.2% for DES levels of 0.5 ng/g and 2.1% for levels of 5 ng/g.