Analytical method development for the simultaneous determination of five human pharmaceuticals in water and wastewater samples by gas chromatography-mass spectrometry

Effective analytical methods for the simultaneous determination of five pharmaceuticals from various therapeutic classes in a variety of aqueous samples have been developed and method performance data are presented. The method involves the simultaneous extraction of the selected pharmaceuticals from the aqueous phase by solid phase extraction using a hyper cross linked, polystyrene-divinylbenzene polymer based sorbent. Analytes were eluted with methanol, derivatised with N-methyl-N-trimethylsilyltrifloroacetamide and analysed by gas chromatography - electron ionisation mass spectrometry (GC-EI-MS). Recoveries of 50 to 98% were established for waters spiked with the studied compounds at the low ng L-1 level with the highest detection sensitivities being achieved in the selected ion monitoring (SIM) mode and the quantification limit of the procedure for sample sizes of 1000 ml was approximately 5 ng L-1 for all matrices except sewage which was only tested to 20 ng L-1. Analysis of domestic sewage from a large treatment works demonstrate the presence of all five compounds in both influents and effluents.