M. A. Elsayed

Spectrophotometric determination of binary mixtures of pseudoephedrine with some histamine H1-receptor antagonists using derivative ratio spectrum method

A derivative spectrophotometric method is developed for the assay of three binary mixtures of pseudoephedrine with fexofenadine (mix I), cetirizine (mix II) and loratadine (mix III). The method is based on the use of the first derivative of the ratio spectrum. The ratio spectrum was obtained by dividing the absorption spectrum of the mixture by that of one of the components. The concentration of the other component was determined from its respective calibration graph treated similarly. Moreover, the influence of Deltalambda for obtaining the first derivative of the ratio spectra and the effect of the divisor concentration on the calibration graphs were studied. The described method was applied for the determination of these combinations in synthetic mixtures and dosage forms. The results obtained were accurate and precise.

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.

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.

Study of stability of methotrexate in acidic solution Spectrofluorimetric determination of methotrexate in pharmaceutical preparations through acid-catalyzed degradation reaction

Study of the degradation reaction of methotrexate (MTX) in acidic solution was carried out. Optimization of the experimental parameters of MTX acid hydrolysis was investigated. Spectrofluorimetric method for determination of MTX through measurement of its acid-degradation product, 4-amino-4-deoxy-10-methylpteroic acid (AMP), was developed. Stability of the standard solution of MTX prepared in sulfuric acid was discussed in the view of accelerated stability analysis. Two other comparative spectroflourimetric methods based on measuring the fluorescence intensities from either a condensation reaction with acetylacetone-formaldehyde (Hantzsch reaction) or a reaction with fluorescamine were also described. Beers law validation, accuracy, precision, limits of detection, limits of quantification, and other aspects of analytical merit are presented in the text. The proposed methods were successfully applied for the analysis of MTX in pure drug and tablets dosage form. The sensitivity of the developed methods was favorable, so it was possible to be adopted for determination of MTX in plasma samples for routine use in high-dose MTX therapy.

Spectrophotometric and titrimetric determination of nizatidine in capsules.

Four simple and accurate methods are described for the determination of nizatidine (NIZ) in pharmaceutical preparations. The first method is based on the formation of an ion-pair complex between the drug and either of bromocresol purple or picric acid with subsequent measurement of the developed colors at 411 and 400 nm, respectively. The second method depends on the condensation of mixed anhydrides of citric acid/acetic anhydride, with the tertiary amino group of the drug, where the developed color is measured spectrophotometrically at 545 nm. The oxidation of nizatidine by N-bromosuccinimide was utilized as a basis for the titrimetric method for its assay in capsules. The last method depends on the oxidation of nizatidine by ammonium cerium IV sulfate in the presence of perchloric acid with subsequent measurement of the absorbance at 314 nm; this principle is adopted to develop a kinetic method for the determination of NIZ in capsules. All the reaction conditions have been studied. The detection limits were varied from 0.44 to 0.78 microg ml(-1). The proposed methods were successfully applied to the assay of nizatidine in capsules.

Computer-assisted spectrophotometry: multicomponent analysis with a discrete fourier transform.

A computer-assisted method for analysis of multicomponent mixtures by use of conventional absorbance as well as discrete Fourier transforin coefficients (combined trigonometric functions) is presented. The program can store absorbance data (A vs. lambda), process data by convolution with combined trigonometric functions, apply least-squares analysis and solve the resultant simultaneous linear equations, and display data on screen, printer or plotter.

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

A stability–indicating first–derivative spectrophotometric assay of acetazolamide and its use in dissolution and kinetic studies

A simple, rapid, stability–indicating first–derivative spectrophotometric assay procedure for the determination of the degradation products of acetazolamide is described. The dissolution and kinetics of drug degradation in aqueous buffered solutions were studied using the proposed method. Acetazolamide solution exhibited optimum stability at pH 4. The influences of temperature and sonic energy on the degradation of acetazolamide in 0–01 M NaOH solution were also studied. The results showed first–order reaction kinetics, with a degradation rate constant and degradation half–life of 31 times 10‐3 day‐1 and 8–23 days, respectively.

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%.

Spectrophotometric determination of ascorbic acid and thiamine hydrochloride in pharmaceutical products using derivative spectrophotometry

Direct spectrophotometric methods for the determination of ascorbic acid (vitamin C) and thiamine hydrochloride (vitamin B1) each in the presence of its degradation product are presented. The methods are based on the use of UV derivative spectrophotometric measurements—the first derivative at 215 nm for ascorbic acid and the second derivative at 254 nm for thiamine hydrochloride. The values obtained are linearly related to the concentration of each vitamin solution and have relative standard deviations of 0.52 and 1.07%, respectively. The mean percentage recoveries for mixtures of each vitamin with their respective degradation product were found to be 101.5 and 99.4%, respectively. Graphs of log C(%m/V)versus time for ascorbic acid solution in 3 N hydrochloric acid and for thiamine hydrochloride solution in buffer at pH 10 were straight lines with slopes of –0.1044 d–1 and –0.0207 h–1, respectively. The methods have been successfully applied to monitor the stability of the vitamins.