1Prof. of Inorganic and Analytical Chemistry, Faculty of Science, Al-Azhar University, Cairo, Egypt
2Prof. of Inorganic and Analytical chemistry, Faculty of Science, Al-Mansoura University, Egypt
3Forensic Chemist, Medico-Legal organization, Ministry of Justice, Cairo, Egypt
Three new, rapid, sensitive, economical and simpler spectrophotometric methods (A—C) have been developed for the microdetermination of diltiazem hydrochloride (DT-HCl) and pipazethate hydrochloride (PZ-HCl) in pure and tablet dosage forms. In method A, simpler direct spectrophotometric measurements in ultra violet region have been developed for the determination of DT-HCl and PZ-HCl without any chemical reagents. A solution of DT-HCl or PZ-HCl in 0.1 M HCl shows maximum absorbance at 238 and 253 nm, respectively. After optimization, the systems obeyed Beer's law in the concentration range of 2—25 and 5—60 μg/mL for DT-HCl and PZ-HCl, respectively. The apparent molar absorptivities were found to be 1.837 x 104 and 7.931 x 103 L mol−1 cm −1 for DT-HCl and PZ-HCl, respectively. Whereas the methods B and C involves the formation of intense yellow ion-association complex between drug(s) and either of phenol red (PR) or chlorophenol red (CPR) reagents followed by extraction with methylene chloride. The ion-associates exhibit absorption maxima at 390 and 402 nm for DT-HCl and at 393 and 405 nm for PZ-HCl with PR and CPR, respectively. After optimization, the systems obeyed Beer's law in the concentration range of 11.28—112.75 and 2.26—48.48 μg/mL for DT-HCl and 8.72—104.64 and 3.27—49.05 μg/mL for PZ-HCl with PR and CPR, respectively. The apparent molar absorptivities were found to be 4.086 x 103 and 9.919 x 103 L mol−1 cm −1 for DT-HCl and 4.212 x 103 and 9.624 x 103 L mol−1 cm −1 for PZ-HCl with PR and CPR, respectively. In methods A— C Sandell's Sensitivity, the slope, intercept, correlation coefficient, relative standard deviation (RSD), detection and quantitation limits were also calculated (n=5) for DT-HCl and PZ-HCl. No interference was observed from common excipients present in pharmaceutical formulations. The results are well compared to those obtained by the reference methods using t-and F-tests. Therefore, the present methods are suitable for the drugs determination, as they are sensitive and precise to a high extent.
UV/VIS Spectrophotometry, Diltiazem hydrochloride, Pipazethate hydrochloride, Phenol red, Chlorophenol red, Tablet dosage forms
