Determination of loperamide hydrochloride in human plasma using LC-MS/MS

Abstract

Objective A LC-MS/MS method for analysis of loperamide hydrochloride in human plasma was developed. Methods Loperamide hydrochloride and berberine hydrochloride (internal standard) were separated from human plasma samples by liquid-liquid extraction with methanol. Chromatographic separation was performed on a ZORBAX SB-C18(2. 1mm × 150mm × 5μm) column at 35°C. Acetonitrile/0. 1% formic acid (60: 40 by volume) was used as mobile phase at a flow rate of 0. 4mL/min, and the injection volume was 10μL. Electrospray ionization(ESI) source was applied and operated in positive ion mode. Quantification was performed using multiple reaction monitoring (MRM) of the transitions m/z 477→266 and m/z 366→ 292 for loperamide hydrochloride and the internal standard, respectively. Results The limit of detection of loperamide hydrochloride was 0. 2ng/mL (S/N = 3), and the calibration curve in the concentration range of 0.5 - 500ng/mL showed a good linear (r = 0. 9982). The average recoveries of low, medium and high concentrations(1 ng/mL, 20ng/mL, 400ng/mL) were 84. 6%, 88.5% and 90. 2%, respectively. The precisions (RSD) of winth-day and between-day were less than 6% and 7%, respectively. Conclusion This LC-MS/MS method can be used for qualitative and quantitative analysis of loperamide hydrochloride.