Determination of hydrochlorothiazide and enalapril maleate in tablet formulations by reversed-phase HPLC

A high-performance liquid chromatographic procedure is presented for the de termination of hydrochlorothiazide (HCT) and enalapril maleate (EM) in phar maceutical tablets. An aliquot of the sample is dissolved in 1.5% acetonitr ile (ACN) containing thiophylline as atl internal standard and chromatograp hed on a Supelcosil LC-8 (5 mum)1 (150 mm x 4.6 mm i.d.) column. The mobile phase was 3.0 mM tetrabutylammoniumhydrogen sulfate (TBAHS) in ACN/water/t riethylamine (TEA), (14, 85.6, 6.4 V/V) adjusted to pH 4.1 by glacial aceti c acid. The detection was at 220 nm. The method was tested for linearity, a ccuracy, recovery. and specificity.