Analysis of acidic drugs in the effluents of sewage treatment plants using liquid chromatography–electrospray ionization tandem mass spectrometry

A liquid chromatography–electrospray ionization tandem mass spectrometry (LC–ESI-MS–MS) method was developed and validated for simultaneous analysis of nine acidic pharmaceutical drugs (bezafibrate, clofibric acid, diclofenac, fenoprofen, gemfibrozil, ibuprofen, indomethacin, ketoprofen and naproxen) in sewage treatment plant (STP) effluents. The mean recoveries of the pharmaceuticals ranged from 58.9 to 91.5% in STP effluent, and the limits of detection of the analytes were 5–20 ng/ml. The method was applied to the quantitative analysis of acidic drugs in the effluents from three Canadian STPs, in which bezafibrate, diclofenac, fenoprofen, gemfibrozil, ibuprofen, indomethacin and naproxen were detected.