Identification and quantification of diethylstilbestrol in the urine of cattle by both low and high resolution gas chromatography mass spectrometry

Abstract

A confirmation method which can be used in regulatory screening programs for diethylstilbestrol in the urine of cattle is presented. trans-Diethylstilbestrol is purified from urine by Sep-Pak extraction and high-performance liquid chromatography and converted into its trimethylsilyl derivative. Identification is based on both accurate mass measurement of the molecular ion of trans-diethylstilbestrol trimethylsilyl by gas chromatography high resolution mass spectrometry and determination of the [M + 1] +/[M]+ peak height ratio by selected ion monitoring in low resolution. Specificity is such that on the basis of mass spectrometric data alone, all molecular formulae except those of diethylstilbestrol trimethylsilyl and only one other compound can be excluded. Additional specificity is provided by chromatographic data. The quantification is based on the standard addition method. The average recovery of trans-diethylstilbestrol is 76% with a standard deviation of 18% (n = 23).