Abstract: Objective To establish a liquid chromatography-tandem mass spectrometry(LC-MS/MS) method for detection of mexiletine by liquid chromatography tandem mass spectrometry. Methods After simple protein precipitation of the blood sample with acetonitrile, the organic solvent layer diluted with LC mobile solvent was separated by Allure PFP Propyl column, confirmed and quantified by MS/MS in the multi-reaction monitoring (MRM) mode via positive electrospray ionization. Results Mexiletine and naloxone (internal standard) got ideal resolution under the selected analytical condition. The correlation coeficient of linear calibration curve was over 0.999 9 within the mexiletine concentration range 0.02-10 μg/mL. The relative standard deviations were under 10% for intra-day and under 15% for inter-day, and the detection limit was 0.01 μg/mL. Conclusion The established LC-MS/MS method is simple, rapid, sensitive, unaffected by matrix effect and appropriate for detection of mexiletine in blood in the field of therapeutic drug monitoring and forensic toxicology.

Key words: LC-MS/MS, anti-arrhythmic drugs, mexiletine, blood