Abstract
Quantitative resolution of the quinapril and hydrochlorothiazide mixture in tablets was achieved by using continuous wavelet transform and chemometric methods. In the case of the continuous wavelet transform, various continuous wavelet families were tested in order to find the optimum point of the wavelet signal processing technique. The Mexican hat wavelet function was reported to be the optimal one. The Mexican hat wavelet function was applied to the absorption spectra of quinapril and hydrochlorothiazide in the spectral range of 200-320 nm for standard series of drugs in the concentration range of 4.0-20.0 µg mL-1 quinapril and 2.5-12.5 µg mL-1 hydrochlorothiazide. The calibration functions for quinapril at 230.6 nm and for hydrochlorothiazide at 271.1 nm were calculated based on the relationship between the measurements of continuous wavelet signals and their concentrations. According to the chemometric approach, partial least squares and principal component regression calibrations were constructed by a training set of 21 mixtures, containing two drugs and their corresponding absorbance data, in the wavelength range of 205-290 nm. All proposed methods were validated by the independent analysis of the synthetic mixtures and by the standard addition technique. The application of the methods indicated that their selectivity and the sensitivity were satisfactory. The investigated methods were successfully applied to tablet analysis.
Highlights
Hydrochlorothiazide (HCT) has diuretic properties and its chemical name is (6-chloro-3,4-dihydro-2H1,2,4-benzothiadizine-7-sulphonamide-1,1-dioxide)
Continuous wavelet transform (CWT) method was extensively used in analytical chemistry, especially, during the last years mainly because it helps in various applications to improve the signal-tonoise ratios, as well as, it was used for data compression
CWT method is a powerful signal processing technique for the overlapping peak resolution and for the significant peak identification. This tool is successfully applied to the spectrophotometric multicomponent analysis of relevant compounds in samples
Summary
Hydrochlorothiazide (HCT) has diuretic properties and its chemical name is (6-chloro-3,4-dihydro-2H1,2,4-benzothiadizine-7-sulphonamide-1,1-dioxide). Quinapril (QU) given by 2-{2-[[1-ethoxycarbonyl)-3phenylpropyl] amino]-1-oxopropyl}-1,2,3,4-tetrahydro3-isoquinoline carboxylic acid is a nonsulfydryl angiotensin-converting enzyme (ACE) inhibitor. It constitutes a family of active compounds used to treat high blood pressure and heart failure. The combination of HCT and QU has been used in pharmaceutical formulation (e.g. Accuzide® tablets) to increase the therapeutic effects. Two studies on the simultaneous analysis of QU and HCT mixture were reported in the literature. TLC method reported in the literature needs a long and tedious analytical process. For these reasons, the analysis of QU-HCT tablets needs new, simple, accurate, selective and sensitive analytical approaches
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