Endocrine disrupting chemicals (EDCs) have been found to have harmful effects on the health of both humans and wildlife. Of these EDCs, endogenous estrogens, such as estriol, 17ß-estriadiol, and estrone are of particular interest due to their potency/physiological activity even at very low levels. These hormones are particularly challenging to monitor, as concentrations are typically expected to be in the low ng/mL (ppb) to low pg/mL (ppt) range.

To improve sensitivity, this work utilizes the addition of on-line solid phase extraction (SPE) coupled to an LC/MS/MS system for sample enrichment and quantitation. This approach allows for significant/efficient analyte concentration, obviating the need for elaborate and time-consuming sample preparation procedures. Due to enrichment, compared to other methods, large sample volumes (= ½ liter) are no longer needed to reach part per trillion levels for estrogen monitoring in river water.