Screening for estrogen residues in calf urine: Comparison of a validated yeast estrogen bioassay and gas chromatography-tandem mass spectrometry

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Within the European Union, the control for residues of illegal hormones in food-producing animals is based on urine analysis for a few target analytes using gas chromatography/mass spectrometry and/or liquid chromatography¿tandem mass spectrometry. Recently, we developed a robust yeast bioassay screening tool for estrogens, which was validated as a qualitative screening method in accordance with EC decision 2002/657/EC. In this study, we present long-term performance data and a comparison of urine data obtained with this bioassay, and data from an established gas chromatography¿tandem mass spectrometry (GC/MS/MS) confirmatory analysis method. More than 120 calf urine samples from a controlled reference experiment were analysed using both protocols. According to the GC/MS/MS method, only the natural estrogens 17¿-estradiol and estrone were present in the non-compliant samples. The bioassay was less sensitive than GC/MS/MS for the relatively weak estrogenic compound 17¿-estradiol, in accordance with expectations. Assuming that application of the mass spectrometric method is considered beyond reasonable doubt, the bioassay performed very well: only 5.6% of the calf urine samples found compliant in GC/MS/MS were screened false suspect in the bioassay screening method. The bioassay results of non-compliant urine samples under routine conditions were as predicted, taking into account the relative estrogenicity of the natural estrogens 17¿-estradiol and estrone vs. 17ß-estradiol. Only one sample was screened false negative for 17¿-estradiol and estrone. Application of this fast and simple estrogen bioassay in routine surveillance and control can significantly reduce GC/MS/MS sample workload and allow higher percentages of animals to be screened for potential hormone abuse
Original languageEnglish
Pages (from-to)1123-1131
JournalFood Additives and Contaminants
Issue number11
Publication statusPublished - 2006


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