Detection of digoxin in urine samples by surface-assisted laser desorption/ionization mass spectrometry with dispersive liquid–liquid microextraction

A novel method for the detection of digoxin using dispersive liquid–liquid microextraction (DLLME) coupled to the surface-assisted laser desorption/ionization mass spectrometric detection (SALDI/MS) was developed. Acetone and chloroform were used as the disperser solvent and extraction solvents, respectively. After the extraction, digoxin was detected using SALDI/MS with colloidal palladium as the matrix. Under optimal extraction and detection conditions, the calibration curve, which ranged from 0.01 to 0.50 μM, was observed to be linear. The limit of detection (LOD) at a signal-to-noise ratio of 3 was 2 nM for digoxin. With a sample-to-extract volume ratio of 400, the enrichment factor for digoxin was calculated to be 252. This novel method was successfully applied for the determination of digoxin in human urine samples.