Liquid chromatography with triple-quadrupole or quadrupole-time of flight mass spectrometry for screening and confirmation of residues of pharmaceuticals in water

LC-MS-MS has been performed with triple-quadrupole (QqQ) and quadrupole-time of flight (Q-ToF) instruments and has been used for screening and confirmation of pharmaceuticals in surface, drinking, and ground water. Screening was based on monitoring of one specific MS-MS ion of the target compounds. Confirmation of the identity of the pharmaceuticals was based either on the monitoring of two specific MS-MS ions and calculation of the ratio of their intensities, or on the exact masses of MS-MS product ions obtained for a molecular ion by use of LC-Q-ToF MS. The set of pharmaceuticals included four analgesics (acetylsalicylic acid, diclofenac, ibuprofen, and paracetamol), three antibiotics (sulfamethoxazole, erythromycin, and chloramphenicol), five blood-lipid regulators and beta-blockers (fenofibrate, bezafibrate, clofibric acid, bisoprolol, and metoprolol), and the anti-epileptic drug carbamazepine. Limits of quantification ranged from 5 to 25 ng L-1. Fifty-six samples were analysed and residues of the pharmaceuticals were detected in almost all surface and groundwater and in some drinking water samples. The identity of the compounds could be confirmed by use of both QqQ- and Q-ToF-based LC-MS-MS. However, the latter technique has the distinct advantage that a large number of pharmaceuticals can be screened and confirmed at low concentrations (1-100 ng L-1) in one run.