Simultaneous determination of natural and synthetic steroid estrogens and their conjugates in aqueous matrices by liquid chromatography/mass spectrometry

An analytical method for the simultaneous determination of nine free and conjugated steroid estrogens was developed with application to environmental aqueous matrices. Solid-phase extraction (SPE) was employed for isolation and concentration, with detection by liquid chromatography/mass spectrometry (LC/MS) using electrospray ionisation (ESI) in the negative mode. Method recoveries for various aqueous matrices (wastewater, lake and drinking water) were determined, recoveries proving to be sample dependent. When spiked at 50 ng/L concentrations in sewage influent, recoveries ranged from 62-89% with relative standard deviations (RSD) <8.1%. In comparison, drinking water spiked at the same concentrations had recoveries between 82-100% with an RSD <5%. Ion suppression is a known phenomenon when using ESI; hence its impact on method recovery was elucidated for raw sewage. Both ion suppression from matrix interferences and the extraction procedure has a bearing on the overall method recovery. Analysis of municipal raw sewage identified several of the analytes of interest at ng/L concentrations, estriol (E3) being the most abundant. Only one conjugate, estrone 3-sulfate (E1-3S), was observed.