Determination of pharmaceutical residues in wastewater using high performance liquid chromatography coupled to quadrupole-Orbitrap mass spectrometry

A multi-class method for the determination of 24 emerging pharmaceutical residues has been developed and validated. The method is based on solid-phase extraction of wastewater samples using Strata-X cartridges followed by high performance liquid chromatography coupled to hybrid quadrupole − Orbitrap high resolution mass spectrometry (HPLC-Q-Orbitrap-HRMS). A single-laboratory validation procedure showed satisfactory analytical performance. The analysis of 21 samples collected at the wastewater treatment plant in Riga revealed the occurrence of 20 compounds of different therapeutic classes. The highest concentration was found for the central nervous system stimulator caffeine − up to 12 μg L−1, the analgesic acetaminophen up to 4.2 μg L−1, the antibiotic ciprofloxacin in the concentration range of 250-400 ng L−1, and the non-steroidal anti-inflammatory drug (NSAID) ibuprofen at 100-325 ng L−1.