Simultaneous determination of five estrogens and four androgens in water samples by online solid-phase extraction coupled with high-performance liquid chromatography–tandem mass spectrometry

A novel method for simultaneous determination of five estrogens and four androgens by online solid-phase extraction (SPE) coupled with high-performance liquid chromatography–tandem mass spectrometry (HPLC–ESI-MS/MS) in water samples was developed. An aliquot of 50 mL water sample after filtration was injected directly into autosampler and the analytes were preconcentrated on a NG1 online SPE column. After cleanup step the analytes were eluted in back flush mode and then separated on a liquid chromatography column. The experimental parameters, such as sample loading flow rate, cleanup condition and elution time, were optimized in detail. Estrogens and androgens were detected in negative and positive mode, respectively. High ionization efficiency of all the analytes was achieved by adding of 1‰ ammonia in the mobile phase. The recoveries ranged from 31.8% to 119.0% and the inter-day RSDs ranged from 2.7% to 19.6%. The limits of detections (LODs) were between 0.1 and 2.5 ng/L. The proposed method was successfully applied to the analysis of three types of water samples, including river water, influent and effluent water from a wastewater treatment plant (WWTP). The recoveries of androgens were not that good and a further study is being planned to improve the sensitivity for them. The proposed method is simple, sensitive and suitable for simultaneous analysis and monitoring of estrogens and androgens in water samples.