Development and validation of a high‐resolution LTQ Orbitrap MS method for the quantification of isoflavones in wastewater effluent

Isoflavones and coumestranes are the most important classes of compounds among phytoestrogens; by binding to estrogen receptors, they mimic or modulate the effect on the endogenous receptors. Little information can be found in literature about the presence of isoflavones and coumestrol in the environment, even if it is known that this may have significance, being these substances classified as endocrine disrupting compounds. In this research, we aim to explore the capabilities of the LTQ Orbitrap Discovery hybridMS in full-scan acquisitionmode, with high resolution, to validate an analyticalmethod for the quantification of nine isoflavones (genistein, genistin, glycitein, daidzein, daidzin, (R,S)-equol, biochanin A, formononetin and coumestrol) in wastewater samples. The correlation coefficients of calibration curves of the nine analyzed compounds were in a range of 0.996–0.999; recoveries at two different levels of concentration (0.05 and 0.5 μg/l) were in the range 73–98%, and the limits of detection ranged between 0.0014 and 0.017 μg/l, proving that thismethod is sensitive enough in comparisonwith othermethods available in literature. This method has been applied for the analysis of 20 wastewater treatment plants in County Cork, Ireland.