Co-precipitation assisted cloud point extraction coupled with high performance liquid chromatography for the determination of estrogens in water and cosmetic samples

A rapid and efficient co-precipitation assisted cloud point extraction is proposed for extraction of five estrogens [17 beta-estradiol (E2), estrone (E1), ethinyl estradiol (EE), diethyl stilbestrol (DES) and dihydro stilbestrol (DHS)] in environmental water and toner samples prior to high performance liquid chromatography analysis. It is based on the combination of co-precipitation with aluminum hydroxide and cloud point extraction with sodium dodecylsulfate to extract the target estrogens. Parameters affecting the extraction of target analytes including the concentration of aluminum hydroxide and sodium dodecylsulfate, extraction time, and blending types were investigated. Under optimum conditions, the enrichment factors were 31.7, 38.5, 28.2, 40.8 and 79.5 for E2, EE, E1, DES and DHS, respectively. A co-precipitation assisted cloud point extraction/high performance liquid chromatography method was developed and the limits of detection (LODs) were in the range of 0.2-0.7 mu g L-1. The proposed method was successfully applied for the determination of trace estrogens in environmental water and toner samples, and the recoveries ranging from 77.3 to 104.1% with RSD of 2.0-10.4% were obtained. Moreover, the present method was compared to the previously reported methods and the extraction mechanism was also discussed. The method was rapid, sensitive and suitable for the trace estrogen analysis.