Multi-residue method for the determination of basic/neutral pharmaceuticals and illicit drugs in surface water by solid-phase extraction and ultra performance liquid chromatography-positive electrospray ionisation tandem mass spectrometry.

The paper presents the development and validation of a new multi-residue method for the determination of 28 basic/neutral pharmaceuticals (antiepileptics, antibacterial drugs, beta-blockers, analgesics, lipid-regulating agents, bronchodilators, histamine-2-blockers, anti-inflammatory agents, calcium channel blockers, angiotensin-II antagonists and antidepressants) and illicit drugs in surface water with the usage of a new technique: ultra performance liquid chromatography-positive electrospray tandem mass spectrometry (UPLC-MS/MS). The usage of the novel UPLC system with 1.7 microm particle size and 1mm internal diameter column allowed for low mobile phase flow rates (0.07 mL min(-1)) and short retention times (from 1.3 to 15.5 min) for all compounds analysed. As a result, a fast and cost-effective method was developed. SPE with the usage of Oasis MCX strong cation-exchange mixed-mode polymeric sorbent was chosen for pharmaceuticals extraction from environmental samples. The influence of matrix-assisted ion suppression and low SPE recovery on the sensitivity of the method was studied. The instrumental limits of quantification varied from 0.2 to 10 microg L(-1). The method limits of quantification were at low nanogram per litre levels and ranged from 0.3 to 50 ng L(-1). The instrumental and method intra- and inter-day repeatabilities were on average less than 10%. The method was applied for the determination of pharmaceuticals in Rivers Taff (UK) and Warta (Poland). Fifteen compounds were determined in river water at levels ranging from single nanograms to single micrograms per litre.