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

The presence of residual pharmaceuticals in the aquatic environment is an important environmental issue. Since the drugs are designed to cause biological responses, they could pose a risk to organisms in their natural environment. In this study, the presence of selected pharmaceutical compounds (paracetamol, phenazone, ketoprofen, budensonide and atenolol) in surface waters was studied. Six sampling points along the aquatic system of the River Louros, close to the city of Ioannina (Epirus, NW Greece), were selected for the assessment of their pollutant load. Analytical method was based on solid-phase extraction of water samples, using Oasis HLB cartridges, followed by high performance liquid chromatography coupled to Orbitrap high resolution mass spectrometry (UHPLC-LTQ/Orbitrap-MS). The methodology exhibited good analytical characteristics (R>65%, R2 >0.9990, LOQs between 1.5 and 11.0 ng/L). Results revealed the presence of only paracetamol (although in levels below LOQ) in two sampling stations. The proposed analytical methodology proved to be fast, easy and reliable for the systematic monitoring of pharmaceuticals residues in natural waters.