Determination of neutral pharmaceuticals in wastewater and rivers by liquid chromatography–electrospray tandem mass spectrometry

An analytical method is presented enabling the determination of nine neutral pharmaceuticals in groundwater, and for most of the compounds, in rivers and wastewater down to the lower ng/l range. The analytes belong to different medicinal groups such as antiphlogistics, psychiatric drugs and antidiabetics. Samples are enriched using solid-phase extraction (SPE) with RP-C18ec material. Analysis is performed by liquid chromatography with detection by electrospray tandem MS. Mean recoveries generally exceed 80% in groundwater, and the quantification limits are down to 50 ng/l in wastewater and down to 10 ng/l in groundwater. Losses were observed to occur either from ion suppression in the electrospray ionisation or SPE. Losses for all compounds could not be compensated for by the surrogate standard dihydrocarbamazepine. In raw municipal wastewater, concentration levels were detected for caffeine up to 147 μg/l and for propyphenazone up to 1.3 μg/l.