Determination of five antiarrhythmic drugs in human plasma by dispersive liquid–liquid microextraction and high-performance liquid chromatography

Abstract

A fast and sensitive high-performance liquid chromatography (HPLC) method with ultraviolet (UV) detection was developed and validated for the simultaneous quantitation of five antiarrhythmic drugs (metoprolol, propranolol, carvedilol, diltiazem, and verapamil) in human plasma samples. It involves dispersive liquid–liquid microextraction (DLLME) of the desired drugs from 660µL plasma and separation using isocratic elution with UV detection at 200nm. The complete separation of all analytes was achieved within 7min. Acetonitrile (as disperser solvent) resulting from the protein precipitation procedure was mixed with 100µL dichloromethane (as an extraction solvent) and rapidly injected into 5mL aqueous solution (pH 11.5) containing 1% (w/v), NaCl. After centrifugation, the sedimented phase containing enriched analytes was collected and evaporated to dryness. The residue was re-dissolved in 50µL de-ionized water (acidified to pH 3) and injected into the HPLC system for analysis. Under the optimal conditions, the enrichment factors and extraction recoveries ranged between 4.4–10.8 and 33–82%, respectively. The suggested method was linear (r2 ≥0.997) over a dynamic range of 0.02–0.80µgmL−1 in plasma. The intra- and inter-days relative standard deviation (RSD%) and relative error (RE%) values of the method were below 20%, which shows good precision and accuracy. Finally, this method was applied to the analysis of real plasma samples obtained from the patients treated with these drugs.