High enrichment factors in chemical analysis of progestins and in bioassays: insights beyond trace levels.

Concerns are growing about adverse effects of progestins on biota, even at ultra-trace concentrations. The enrichment factor (EF) from extraction of analytes in environmental samples that is needed for sample pre-concentration can affect not only performance of the analytical method but also the matrix effect. Therefore, the present study aimed to assess the influence of high sample EF on performance of the high-performance liquid chromatography with atmospheric pressure chemical ionization and photoionization coupled with high-resolution mass spectrometry (HPLC-APCI/APPI-HRMS) method for analysis of progestins in waste water treatment plant (WWTP) effluents and surface waters and analysis of (anti-)progestogenic activities measured by (anti-)PR-CALUX bioassays. The results showed that HPLC-APCI/APPI-HRMS coupled with solid-phase extraction and a high EF (33,333 L/L) enabled the detection of more compounds compared to samples with lower sample EF (10,000 L/L). The matrix effect did not increase proportionally compared to lower EFs (10,000 and 16,666 L/L), and lower limits of quantification were achieved in WWTP effluents and surface waters. The results of bioassays have shown that relative EF of 25 L/L appears high enough to detect progestogenic activity in treated waste water. Our study is one of the first to provide insights into sample pre-concentration in analysis of progestins and progestogenicity in aquatic environments.