M. A. Korany

First Derivative Spectrophotometric Determination of Certain Drugs in Two-Component Mixtures

Abstract Four two-component mixtures have been assayed using both Vierordts and first derivative spectrophotometric methods. Such mixtures are acepifylline and phenobarbitone, phenylbutazone and amidopyrine, procaine and caffeine, and sulphamethoxazole and trimethoprim. These selected applications illustrate the relative ease and simplicity offered by first derivative spectrophotometry for the assay of two component mixtures with spectral interferences from matrix formulations.

Spectrophotometric and high performance liquid chromatographic determination of cetirizine dihydrochloride in pharmaceutical tablets

Derivative spectrophotometric, colorimetric and high performance liquid chromatographic methods, for the determination of the antihistaminic cetirizine dihydrochloride in tablet form were described. Spectrophotometrically, cetirizine was determined by the measurement of its first (1D) and second (2D) derivative amplitudes at 239 (peak) and 243-233 nm (peak-to-trough), respectively. The aqueous solutions obeyed Beers law in the concentration ranges of 1.2-10.0 and 0.8-10.0 micrograms ml-1 for 1D and 2D measurements, respectively. The colorimetric procedure was based on measuring the absorbency of the coloured chromogen resulted from the reaction between cetirizine sodium salt in polar solvent (DMF) and chloranil at 556 nm. The relation with concentrations was linear over 120-250 micrograms ml-1. Optimization of the reaction conditions was studied. At the same time, investigation of the complex formed was made with respect to its composition and the associated constant. A simple liquid chromatographic assay has been developed for the determination of cetirizine dihydrochloride in the presence of one of its synthesis precursor (hydroxyzine hydrochloride). A Bondapak-C18 column was used with a mobile phase consisting of acetonitrile/0.01 M ammonium dihydrogen phosphate (32:68, v/v) containing 0.1% w/v tetrabutyl ammonium hydrogen sulphate adjusted to pH 3 with phosphoric acid at a flow rate of 2 ml min-1. With salicylic acid as internal standard, quantitation was achieved with UV detection at 230 nm based on the peak height ratios. Beers law was obeyed in a concentration range of 3-35 micrograms ml-1 and the regression line equation was derived with a correlation coefficient of 0.9999. The validity of the methods was further confirmed using the standard addition method. The proposed procedures were successfully applied to the determination of cetirizine in bulk and tablet form, with high percentage of recovery, good accuracy and precision.

Determination of Certain Drugs in Multicomponent Formulations by First Derivative Ultraviolet Spectrophotometry

Abstract The use of first derivative spectrophotometry for the simultaneous determination of certain drugs in multicomponent formulations is presented. The method is illustrated by the determination of antazoline hydrochloride, phenylephrine hydrochloride and ephedrine hydrochloride in eye drops and acepifylline, phenobarbitone and papaverine hydrochloride in suppositories. These selected applications illustrate the relative ease and simplicity offered by first derivative spectrophotometry for the assay of three-component mixtures with spectral interferences from matrix formulations.

Spectrofluorimetric determination of three pharmaceutical thiocompounds and allopurinol using mercurochrome

Abstract A new, simple and sensitive fluorimetric method for the determination of three pharmaceutical thiocompounds: cimetidine, thiabendazole and carbimazole, and also allopurinol, has been presented. The method is based on the fluorescence quenching of mercurochrome (MER) in an aqueous alkaline medium. Calibration graphs correlating the fluorescence difference (Fo-F) or the fluoresence ratio (Fo/F) of MER before (Fo) and after (F) quencher addition versus the concentration of the latter are linear. Such linearity permitted the successful application of

Use of orthogonal polynomials for unequal intervals to eliminate interference in spectrophotometric analysis. Simultaneous determination of ephedrine hydrochloride and diphenhydramine hydrochloride in two-component mixtures

A general method is outlined for the use of orthogonal polynomials for unequal intervals to eliminate interferences in two-component spectrophotometric analysis. The method is particularly useful when (i) the optimum conditions of Vierordts method are not fulfilled and (ii) the two absorption spectra have considerable overlap. The method is illustrated by the determination of ephedrine hydrochloride and diphenhydramine hydrochloride in binary mixtures. The results obtained are encouraging and suggest that the method can be widely applied to similar problems.

Derivative Spectrophotometric Determination of Some Tranquilizer - Antidepressant Mixtures

Abstract A method is presented for the determination of three tranquilizer-antipressant mixtures namely perphenazine amitriptyline, chlordiazepoxide-amitriptyline and trifluoperazine-isopropamide. The method depend on the application of first and second derivative spectrophotometric methods to resolve the interferance due to spectral overlapping. The method was applied to the determination of these compounds in synthecic mixtures and in pharmaceutical preparations. The coefficient of variation was less than 2%.

Analysis of Diphenhydramine Hydrochloride and Naphazoline Hydrochloride in Presence of Methylene Blue in Eye Drops by Second Derivative Spectrophotometry

AbstractA second (D2) derivative spectrophotometric technique has been applied for the determination of diphenhydramine hydrochloride in mixture with naphazoline hydrochloride and in presence of Methylene blue. Diphenhydramine hydrochloride has been extracted with chloroform and D2-value was measured at 255 nm. Naphazoline hydrochloride in the mixture has been determined by direct measurement of its D2 at 273 nm. Methylene blue could be determined in the mixture by direct absorbance measurement at 663 nm. As illustrate example, commercial eye drops was analysed for these two drugs in presence of methylene blue in pharmaceutical preparation. The results obtained were of high accuracy and good reproducibility.

Colourimetric determination of pharmaceutical thiocompounds and allopurinol using mercurochrome

Abstract A new, simple and sensitive colourimetric method for determination of three pharmaceutical thiocompounds: cimetidine, thiabendazole and carbimazole, and also allopurinol, has been presented. the method is based on the reaction of each drug with mercurochrome (MER) in aqueous alkaline medium to give an intense red coloured chromogen. Optimization of the reaction conditions has been investigated. Obedience to Beers law permitted the successful application of the proposed method for the assay of the investigated drugs in different dosage forms. Compared with the Pharmacopoeial methods, the proposed method gave equally accurate (t-test) and precise (F-test) results.

Stability Indicating First Derivative Sfectrophotometric: Assay for Nifedipine in Its Pharmaceutical Preparations on a Diode Array Spectrophotometer

Abstract A simple, rapid and accurate method for the simultaneous determination of nifedipine and its photodecom position products, without prior separation, is presented. The quantitation of nifedipine and its photodecom-posltion products were achieved by first derivative spectroscopy on a diode-array spectrophotometer. Both the nifedipine and the photodecompositlon products can be assyed in dasage forms by measurements of the amplitude of respectively, the peak at 402 nm and the zero crossing at 282 nm and 332 nm. The method is proved using synthetic mixtures of the intact drug with its photodecomposition products. The rate of the photodecomposition products. The rate of the photodecomposition of nifedipine to its nitroso-derivative, using fluorescent light in ethanol and in the base used as excipient in the soft gelatin capsules, was studied.

SPECTROPHOTOMETRIC DETERMINATION OF CIMETIDINE IN THE PRESENCE OF ITS ACID-INDUCED DEGRADATION PRODUCTS

Cimetidine has been determined in the presence of its acid-induced degradation products using a second derivative (D2-) spectrophotometric method (method I) or a colorimetric method (method II). The former is based on D2-value measurement at 216 nm, whilst the latter depends on charge-transfer complexation with dichlorophenol-indophenol. The two methods are proved to be stability indicating, since plots of log C% versus time were linear. The application to cimetidine determination in tablets and ampoules gave good results.