Detection of pharmaceuticals and their transformation products in seawaters using off-line solid phase extraction and liquid chromatography-high resolution mass spectrometry

Aim: Fast urbanization of free land, industrial progress, and improvement of human life quality, have led to increased consumption of different chemical substances recognized as emerging contaminants (ECs) that are chemicals posing potential risks to the environment and human health, but are not yet subjected to regulatory criteria. Pharmaceuticals consumed by humans are continuously discharged into aquatic environments through urban effluents and numerous classes of them have been widely detected in surface waters. We have to highlight that pharmaceuticals, deposited in the aquatic environment end up in human body through the consumption of marine organisms. Consequently, seawater can be considered as feed. Aim of the study is the development, optimization and validation of a multi-residue analytical method concerning the detection of pharmaceuticals in seawaters. Methods: The present study describes the development of a highly selective and sensitive analytical method using solid phase extraction (SPE) followed by UHPLC-LTQ/Orbitrap MS for the determination of 18 frequently prescribed pharmaceuticals and 3 transformation products (TPs) in seawater. In order to optimize the extraction method different cartridge types were tested. Results: Main results showed that the appropriate type of sorbent was concluded to be Oasis HLB, which presented the highest recoveries fluctuating between 61.6% and 118.8%, with a relative standard deviation below 4% and below 5%, for intra-day and inter-day precision, respectively. Limits of detection (LODs) ranged from 0.3 ng L–1 for venlafaxine to 9.8 ng L–1 for oxolinic acid, and the limits of quantification (LOQs) ranged from 1.2 ng L–1 for carbamazepine to 26.4 ng L–1 for oxolinic acid, while in all cases, the linearity, as measured by the correlation coefficient, was greater than 0.991 and ranged within the method’s quantification limit for each chemical and 1,000 ng L–1. Conclusions: Concerning the conclusions positive detections were found in the seawater samples for oxytetracycline, sulfadiazine, caffeine, paracetamol, and trimethoprim.