Rapid Biological Methods Of Estrogen Detection In Waters

To detect the major estrogens in Shanghai waters, the two kinds of rapid, sensitive and effective biological methods, enzyme-linked immunosorbent assay (ELISA) and yeast two-hybrid assay, were introduced. The results showed that the standard curves of ELISA were linear (R2>0.98) and reproducible (Pearson coefficient of correlation>0.99). Testing of 1μg/L standard estradiol (E2) solution by ELISA showed that the recovery ratio was 92～118%, relative error was 8～18%, coefficient of variation (CV) was less than 30%. By using solid phrase extraction (SPE)-ELISA to detect the E2 contents in real samples,0.5 ng/L of the detection limit and 3～24% of the CV were obtained. Although the results produced by the ELISA tended to be overestimated (2～10 times higher than that of LC-MS/MS), a good correlation (R2=0.9526) was obtained. ELISA was applicable for not only high throughput screening of environmental estrogens but also initial estimation of target estrogen in samples without the presence of mass-based analysis equipments. Testing of the two-hybrid yeast strain to 17β-estradiol (E2) showed that the yeast two-hybrid assay had good dose-response relationship (R2=0.995) and high sensitivity (EC50=5.73×10-11 mol/L). By using the yeast two-hybrid assay to detect the total estrogenic activities in real samples,6 ng/L of the detection limit and 1～17% of the CV were obtained. By comparing the results of the yeast two-hybrid assay and that calculated by LC-MS/MS, they were significantly different (R2= 0.2756). The major applications of the yeast two-hybrid assay was to test water samples containing high estrogen contents and showing high environmental risks, such as sludge and sewage treatment plant samples, and to evaluate the anti-estrogenic/estrogenic effects and QSAR (quantitative structure-activity relationship) of compounds.