Direct Analysis of Six Pharmaceuticals using Online Solid Phase Extraction Liquid Chromatography

In this study, three parameters (sample volume, cleanup and elution step) in large volume injection online Solid Phase Extraction Liquid Chromatography with diode array detection (SPE-LC) were optimized for the determination of six pharmaceuticals in wastewater samples. Preconcentration and separation were carried out using 2 columns, Dionex Ion Pac AG14A and Acclaim Polar Advantage II. Response Surface Methodology (RSM) was employed for the optimization of cleanup step (mobile phase composition and valve switching time). The optimum conditions obtained were as follows: Sample volume of 10.0 mL and cleanup with acetonitrile and ultrapure water (5:95) for 1.0 min. The method showed good recovery (82.91-107.7%), precision (0.35-8.26%) and linearity (R² >0.99). The limit of detection was between 3.5 and 11.7 μg L^-1. The proposed method is rapid, simple and sensitive for trace analysis of pharmaceuticals in water samples.