Dispersive liquid-liquid microextraction for the quantification of venlafaxine in environmental waters

The present work describes a new methodology for the detection of the antidepressant venlafaxine (VEN) in aquatic environments using dispersive liquid-liquid microextraction followed by high performance liquid chromatography with fluorescence detection (DLLME-HPLC-FLD). The method developed is fast, low cost, easy to apply, uses a small volume of organic solvents and allows the simultaneous extraction of various samples. The DLLME-HPLC-FLD method presented a linearity range from 25 to 1500 ng L^-1, a detection limit of 24.2 ± 0.2 ng L^-1, and an enrichment factor of 75 ± 4. Recovery tests using solutions of NaCl and humic acids showed that ionic strength and organic matter do not influence the efficiency of the extraction, with extraction recoveries above 77%. Finally, the optimized method was applied to the analysis of water samples from different origins and VEN was only detected in one water sample obtained from a waste water treatment plant (WWTP), which had a concentration of 175 ± 5 ng L^-1. Recovery tests performed in environmental aquatic samples demonstrated that the developed extraction procedure is not influenced by the complex water matrices, with results ranging from 76 to 93%.