Combination of high-performance thin-layer chromatography with a specific bioassay - A tool for effect-directed analysis

The objective of this study was to combine the Yeast Estrogen Screen (YES) for the detection of estrogenic compounds with thinlayer chromatography. Such an approach might serve as an effective tool in effect-directed analysis, i.e., the identification of bioactive compounds in mixtures. The proposed method (planar-YES) allows the detection of estrogenic effects on the surface of a TLC plate after an exposure time of 2-3 h instead of the usual 18 h which are used for the traditional microplate-YES. The estimated limits of quantification for the estrogenic model compound 17α-ethinylestradiol (EE2) were 0.8 pg without and 1.6 pg with a prior chromatographic development of the TLC plate. The hormones 17α- ethinylestradiol (EE2), 17β-estradiol (E2) and estrone (E1) could be separated by thin-layer chromatography and were detected by means of the specific bioassay subsequently. Finally, the applicability of the method on real samples was demonstrated with the detection of estrogenic effects in sediment extracts from sediments of the river Elbe.