Direct sub-ppt detection of the endocrine disruptor ethinylestradiol in water with a chemiluminescence enzyme-linked immunosorbent assay Original Research Article

A chemiluminescence ELISA for the direct detection of ethinylestradiol (EE2) in water at sub-ppt levels was developed and validated. At a signal-to-noise ratio of three the detection limit is 0.2 ± 0.1 ng L−1, at a ratio of 10 the LOQ is found to be 1.4 ± 0.8 ng L−1. Based on a conservatively calculated precision profile the analytical working range is established from 0.8 to 100 ng L−1. The ELISA was tested in four different matrices, including surface water and effluent of sewage treatment plants. All measurements were validated using an LC–MS/MS method. Typical results were consistent in both methods below 1 ng L−1. Using this chemiluminescence ELISA facilitates for the first time the direct detection of EE2 at ecotoxicologically relevant concentrations.