Estrogens and their conjugates: Determination in water samples by solid-phase extraction and liquid...

A sensitive method for simultaneously determining eleven free and conjugated steroid estrogens has been developed using liquid chromatography-(electrospray)triple quadrupole-mass spectrometry (LC-(ESI)MS-MS) in negative mode with application to environmental aqueous matrices. Two selected reaction monitoring (SRM) transitions per compound were used, one of which was used for quantification and the second one for confirmation. The procedure includes a solid-phase extraction with an Oasis HLB solid-phase cartridge. Recoveries in 500 mL of river water spiked at 50 ng/L for sulfate estrogens and 100 ng/L for the rest of the compounds were 46-87%, except for E2, which had lower values (32%). Recoveries in wastewater were higher than 49% and 30% for all the compounds, except E2-17A and E2-17G (lower than 26% and 28%, respectively), in effluent (250 mL) and influent (100 mL), respectively. Ion suppression is a well-known phenomenon when using ESI; thus its impact on method recovery made us consider this effect when quantifying our samples. Limits of detection varied from 2 to 30 ng/L in river water and 10 to 100 ng/L in sewage water. The method was used to determine the target compounds in the Ebro river water where none of the analytes were found. In effluent and influent water samples, EE2, E1-3S and E2-3S were determined at concentration levels ranging from 35 to 160 ng/L.