Determination of acidic pharmaceutical products and carbamazepine in roughly primary-treated wastewater by solid-phase extraction and gas chromatography–tandem mass spectrometry

Abstract

A gas chromatography–tandem mass spectrometry (GC–MS/MS) method has been developed for the determination of selected pharmaceutical residues (carbamazepine, salicylic acid, clofibric acid, ibuprofen, 2-hydroxy-ibuprofen, fenoprofen, naproxen, ketoprofen, diclofenac, and triclosan) in sewage influent and roughly primary-treated effluent. The method involved solid-phase extraction (SPE) with polymeric sorbents, and two SPE cartridges were compared for the extraction and elution of the targeted compounds in complex matrices. A successful chemical derivatization of carbamazepine and acidic compounds using N,O-bis(trimethylsilyl) trifluoroacetamide +10% trimethylchlorosilane is also described. The quantification limits of the analytical procedure ranged from 30 to 60 ng L−1 for 500 mL of wastewater. The best recovery rates (72–102%) in spiked effluent samples were obtained with Phenomenex Strata-X™ cartridges. Detection limits (S/N = 3) were estimated at between 1 and 18 ng L−1. The reported GC–MS/MS method significantly reduces the strong matrix effects encountered with more expensive LC-MS/MS techniques. Application of the developed method showed that most selected analytes were detected at concentrations ranging from low µg L−1 to trace level ng L−1 in Montreal's wastewater treatment plant effluent and influent, as well as in the receiving waters at more than 8 km downstream of the effluent outfall. The rugged alternative analytical method is suitable for the simultaneous analysis of carbamazepine and pharmaceutical acidic residues in wastewater samples from influents and effluents that have undergone rough primary treatment.