Development of solid-phase extraction method and its application for determination of hydrochlorothiazide in human plasma using HPLC

A high‐performance liquid chromatographic method was developed, validated and applied for the determination of hydrochlorothiazide in human plasma. The effects of mobile phase composition, buffer concentration, mobile phase pH and concentration of organic modifiers on retention of hydrochlorothiazide and internal standard were investigated. The method involves solid‐phase extraction on RP‐select B cartridges followed by isocratic reversed‐phase chromatography on a Hibar Lichrospher 100 RP‐8 column with UV detection at 230 nm. The recovery, selectivity, linearity, precision and accuracy of the method were evaluated from spiked human plasma samples. Limit of quantification was 10 ng mL−1. The method has been implemented to monitor hydrochlorothiazide levels in patient samples. Copyright © 2004 John Wiley & Sons, Ltd.