Quantitative determination of diethylstilboestrol in bovine urine with isotope dilution mass spectrometry

A method has been described for the quantification of diethylstilboestrol (DES) in bovine urine. The determining step is based on isotope dilution mass spectrometry (IDMS). The chemical work-up consisted of enzymatic deconjugation, Sep-Pak clean-up and high-performance liquid chromatography (HPLC). The labelled compound synthesized for IDMS is hexadeutero DES (DES-2H6). The labelled compound is not only used to quantify DES, but also to check the recovery of the chemical work-up procedure, in order to avoid false negative results. At the 1-5 micrograms l-1 level of urinary DES, the average recovery of 2 micrograms l-1 DES-2H6 is 70 +/- 20% (s.d.).