Simultaneous Determination of 13 Psychiatric Pharmaceuticals in Sewage by Automated Solid Phase Extraction and Liquid Chromatography-Mass Spectrometry

A method has been developed for the determination of 13 psychiatric pharmaceuticals in wastewater by automated solid phase extraction-high performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (ASPE-HPLC-ESI-MS/MS) in positive ion mode and multiple reactions monitoring (MRM). The ASPE extracts were further purified using an amino SPE cartridge prior to HPLC analysis. HPLC separation was performed on an Waters X-bridge C-18 column utilizing a gradient elution program of the organic mixture (acetonitrile : methanol = 50:50 (V/V)) and ammonium formate buffer solution (containing 0.2% formic acid, and adjusted to pH 3.5 with ammonium hydroxide) as the mobile phase. Recoveries of all analytes from matrix spiking experiments in the sewage WWTP's influent and effluent at three concentrations ranged from 93.2% to 106.8%. The matrix effects were 77.3%-98.6% except that for citalopram. Method detection limits for 4, 4 and 5 analytes in the sewage WWTP's influent and effluent were <1.5, 4-12 ng/L and 20-80 ng/L, respectively. Based on this method, 11 psychiatric pharmaceuticals were detected in 35 wastewater samples from sewage WWTPs except clonazepam and fluvoxamine.