Simultaneous Densitometric Determination of Quinapril and Hydrochlorothiazide in the Combination Tablets

摘要

A new, simple, and accurate TLC method, using normal- and reversed-phase techniques and densitometric detection, has been developed for measurement of quinapril and hydrochlorothiazide in combination tablets. UV detection at A = 210 nm was used to quantify the analytes. The drugs were chromatographed on silica gel 60 F2S4 HPTLC plates and on octadecilsilane (RP-18) TLC plates, in horizontal chambers, with ethyl acetate-acetone-acetic acid, 8 + 2 + 0.5 (v/v) and methanol-0.07 M phosphate buffer, pH 2.5, 6 + 4 (v/v), respectively, as mobile phases. The active substances were extracted from tablets with methanol (96% < mean recovery < 104%). Calibration curves were constructed in the range 0.4 to 2.4 mug muL~(-1) for quinapril and 0.25 to 1.5 mug muL~(-1) for hydrochlorothiazide, with good correlation (r> 0.998). The precision (RSD < 4.4%) and accuracy (2.91 < RE < 3.92) were satisfactory for TLC-densitometric determination of quinapril in combination with hydrochlorothiazide in commercial tablets.