RT preprint T1 Determination of Pharmaceuticals in Coastal Systems Using Solid Phase Extraction (SPE) Followed by Ultra Performance Liquid Chromatography – tandem Mass Spectrometry (UPLC-MS/MS) A1 Baena Nogueras, Rosa María A1 Pintado Herrera, Marina Guadalupe A1 González Mazo, Eduardo A1 Lara Martín, Pablo Antonio A2 Química Física K1 Antibiotics K1 estuary K1 mass spectrometry K1 pharmaceuticals K1 seawater K1 solid phase extraction AB This paper describes the optimization and validation of an analytical method for the determination of 83 pharmaceutically active compounds (PhACs) in aqueous samples using solid-phase extraction (SPE) followed by ultra performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-QqQ-MS/MS). First, several experiments were conducted to optimize different SPE extraction parameters such as pH, elution solvents, and Na2EDTA addition. Extraction recovery percentages were between 17 and 146%, being higher than 70% for 47 target analytes. The effect of salinity in the extraction efficiency proved to be negligible (< 20% within a range from 0 to 38 g L-1). The method limits of detection (LOD) and quantification (LOQ) were below 1 ng L-1 for most compounds (> 90%), and the precision of the method, calculated as the relative standard deviation (RSD) of replicate extractions and analyses, was less than 20%. The optimized method was successfully applied to the analysis of real water samples in estuarine and coastal systems from SW Spain (Cadiz Bay and Huelva Estuary). 49 out of 83 target compounds were found in 75% of samples. Ibuprofen, atenolol, gemfibrozil and caffeine were the most commonly detected substances, reaching concentrations up to 195 ng L-1. PB Samuel Achilefu SN 1875-6727 YR 2015 FD 2015-10-01T00:00:00Z LK http://hdl.handle.net/10498/17946 UL http://hdl.handle.net/10498/17946 LA eng DS Repositorio Institucional de la Universidad de Cádiz RD 08-nov-2026