Simultaneous Determination of Hydrochlorothiazide and Reserpine in Human Urine by LC with a Simple Pre-Treatment.

A simple, selective and sensitive reversed-phase high performance liquid chromatography method for simultaneous analysis of hydrochlorothiazide and reserpine in human urine was developed and subjected to primary pharmacokinetic study. After a simple protein precipitation using methanol and extraction with ethyl acetate, the analytes were separated on an Elite C(18) column at a flow rate of 0.8 mL min(-1). The mobile phase was composed of acetonitrile (A) and 0.2% ammonium chloride solution (B) for a gradient elution starting at A:B at 30:70, v/v for 0~6 min, linearly raising the percent of A from 30% to 50% (6~9 min) and ending at 50:50, v/v (9~25 min). The standard curves were linear over the range of 0.05-20 µg mL(-1) for hydrochlorothiazide and 0.02-5.0 µg mL(-1) for reserpine, respectively (r > 0.999). The limit of detection (LOD) and the limit of quantification (LOQ) were 5.5 ng mL(-1) and 18.2 ng mL(-1) for hydrochlorothiazide, and 7.1 ng mL(-1) and 23.6 ng mL(-1) for reserpine, respectively. The recoveries for both analytes were above 89.0±1.35%. The intra-day and inter-day precision for hydrochlorothiazide were less than 1.91% and 1.38%, and those for reserpine were below 1.61% and 2.64%, respectively. The method indicated good performance in terms of specificity, linearity, detection and quantification limits, precision and accuracy, and it was employed successfully for the simultaneous determination of hydrochlorothiazide and reserpine in human urine samples.