Application of tandem dispersive liquid-liquid microextraction for the determination of doxepin, citalopram, and fluvoxamine in complicated samples.

A new type of dispersive liquid-liquid microextraction is used for the determination of doxepin, citalopram, and fluvoxamine in aqueous matrices. This method is based upon the tandem utilization of dispersive liquid-liquid microextraction, and by providing a high sample clean-up, it efficiently improves the applicability of the method in complicated matrices. For this purpose, in the first step, the analytes contained in an aqueous sample solution (8.0 mL) were extracted into an organic solvent, and then these analytes were simply back-extracted into an aqueous acceptor phase (50 μL). The overall extraction time was 7 min, and very simple tools were required for this aim. Optimization of the variables affecting the method such as the type and volume of the organic solvent used and effect of ionic strength was carried out to achieve the best extraction efficiency. Under the optimized experimental conditions, tandem dispersive liquid-liquid microextraction with high-performance liquid chromatography and UV detection showed a good linearity in the range of 10-5000 ng/mL. The limits of detection were in the range of 3-10 ng/mL. The Intra-day precisions (relative standard deviation) were 9.2, 4.5, and 4.8, and the recoveries were 58.5, 52.9, and 39.3% for citalopram, doxepin, and fluvoxamine, respectively.