Comparison of Directly Suspended Drop Microextraction with Dispersive Liquid-liquid Microextraction Method for Extraction of Doxepin in Water and Biological Samples Prior to UV-Vis Spectrophotometer

The present research describes the use of directly suspended drop microextraction and air-assisted dispersive liquid-liquid microextraction method coupled with UV-Vis spectrophotometer for the analysis of doxepin in water and biological samples. Several important parameters which influence the extraction efficiencies of these two microextraction methods, such as the kind of extracting solvent, volume of the aqueous sample solution (donor phase), volume of the organic extraction solvent (acceptor phase), pH of the donor phase, salt effect, extraction time, stirring rate and number of the air injection were investigated. Under the optimal conditions the enrichment factors were above than 30. The linearity of the methods has been investigated between the ranges of 0.005-1.5 and 0.003-1 μg/mL. The precisions of two methods which are based on the average relative standard deviations are lower than 6, for three different concentrations of the analyte. Finally, the proposed methods were applied for the determination of doxepin in real samples including environmental water, urine and human plasma samples under the optimal conditions and the reasonable relative recoveries were obtained.