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A scheme of bioassay-directed analysis has been developed which combines a yeast assay screening for estrogenic activity with a liquid chromatographic-mass spectrometric (LC-MS/MS) chemical analysis, chromatographic fractionation, solid phase extraction and freeze-drying. The test scheme was applied on effluent samples collected from a municipal sewage treatment plant. The aim was to determine the substances responsible for main portion of the estrogenic activity in the samples and to compare the efficiency of different procedures for isolation and concentration of estogenicity. LC-MS/MS analyses were used for the quantification of 17 beta-estradiol, estrone, estriol and 17 alpha-ethinylestradiol, and the measured concentrations compared with the activities found in the yeast assay. Following conversion of the concentrations measured by LC-MS/MS to 17 beta-estradiol equivalents it was concluded that freeze-drying, solid phase extraction and the chemical analysis gave comparable activities. Since estrone was the major estrogen in the effluent, this estrogen was also the major contributor to the estrogenic activity in the effluent. The estrogenic activity was equivalent to 4-7 ng/L of 17 beta-estradiol. The yeast assay results from the tests of the chromatographic fractions showed that the major activity resides in the fraction where estrone, 17 beta-estradiol and 17 alpha-ethinylestradiol eluted. The activity of this fraction was substantially higher than the activity of the original wastewater sample. The reason for this could in part be explained by an inhibition of activity occurring in the original water sample. (c) 2007 Elsevier BN. All rights reserved.
Fields of Science
- 1182 Biochemistry, cell and molecular biology
- 219 Environmental biotechnology