Stability indicating spectrophotometric methods for quantitative determination of carbamazepine and its degradation product, iminostilbene, in pure form and pharmaceutical formulations

Abstract Ratio subtraction and isosbestic point methods are 2 innovating spectrophotometric methods used to determine vincamine in the presence of its acid degradation product and a mixture of cinnarizine (CN) and nicergoline (NIC). Linear correlations were obtained in the concentration range from 840 g/mL for vincamine (I), 622 g/mL for CN (II), and 636 g/mL for NIC (III), with mean accuracies 99.72 0.917 for I, 99.91 0.703 for II, and 99.58 0.847 and 99.83 1.039 for III. The ratio subtraction method was utilized for the analysis of laboratory-prepared mixtures containing different ratios of vincamine and its degradation product, and it was valid in the presence of up to 80 degradation product. CN and NIC in synthetic mixtures were analyzed by the 2 proposed methods with the total content of the mixture determined at their respective isosbestic points of 270.2 and 235.8 nm, and the content of CN was determined by the ratio subtraction method. The proposed method was validated and found to be suitable as a stability-indicating assay method for vincamine in pharmaceutical formulations. The standard addition technique was applied to validate the results and to ensure the specificity of the proposed methods.

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Stability-Indicating Methods for Determination of Pyritinol Dihydrochloride in the Presence of Its Precursor and Degradation Product by Derivative Spectrophotometry

Journal of AOAC International ◽

10.1093/jaoac/88.1.80 ◽

2005 ◽

Vol 88 (1) ◽

pp. 80-86 ◽

Cited By ~ 3

Author(s):

Mostafa A Shehata ◽

Mohammad A El-Sayed ◽

Mohammad G El-Bardicy ◽

Mohammad F El-Tarras

Keyword(s):

Hydrochloric Acid ◽

Degradation Product ◽

Pharmaceutical Formulations ◽

Zero Crossing ◽

Stability Indicating ◽

First Derivative ◽

Linear Relationships ◽

Assay Methods ◽

Powdered Form

Abstract A first-derivative spectrophotometric (1D) method and a derivative-ratio zero-crossing spectrophotometric (1DD) method were used to determine pyritinol dihydrochloride (I) in the presence of its precursor (II) and its degradation product (III) with 0.1N hydrochloric acid as a solvet. Linear relationships were obtained in the ranges of 6–22 μg/mL for the (1D) method and 6–20 μg/mL for the (1DD) method. By applying the proposed methods, it was possible to determine pyritinol dihydrochloride in its pure powdered form with an accuracy of 100.36 ± 1.497% (n = 9) for the (1D) method and an accuracy of 99.92 ± 1.172% (n = 8) for the (1DD) method. Laboratory-prepared mixtures containing different ratios of (I), (II), and (III) were analyzed, and the proposed methods were valid for concentrations of ≤10% (II) and ≤50% (III). The proposed methods were validated and found to be suitable as stability-indicating assay methods for pyritinol in pharmaceutical formulations.

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