In this study, dispersive liquid-liquid microextraction method was employed for the extraction and preconcentration of digitoxin in an aqueous solution. The analyte was detected by the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.The appropriate mixture of 1 mL of dispersive solvent (tetrahydrofuran, THF)and 12 μL of extraction solvent (chloroform, CHCl3) was injected into a standard solution of digitoxin. After centrifugation, the extraction solvent was deposited on the bottom of the conical tube. The sediment phase was transferred and mixed with a-CHCA matrix before analyzing by a mass spectrometer.The results of our experimental data for the determination of digitoxin showed the signal enhancement factor of this analyte could be as high as 1,200 after dispersive liquid-liquid microextraction. The limit of detection of digitoxin was 2.2 nM, the linear dynamic range was from 0.05 μM to 1 μM with a correlation coefficient (R2) of 0.9998, respectively and the relative standard deviation was within 10%.The analytical method we proposed had also been successfully applied for the
determination of digitoxin in biological fluids such as urine after simple pretreatment procedure. The advantages of this technique are fast, simple, easy sample preparation,high sensitivity and high selectivity.