M. Abdel-Hady Elsayed

Spectrophotometric determination of acetaminophen and salicylamide through nitrosation and subsequent chelation

A nitrosation reaction has been adopted for the spectrophotometric determination of acetaminophen and salicylamide. The selectivity of the reaction is increased through utilisation of the nitroso derivatives as chelating agents for cobalt(II) and copper(II) ions. The optimum experimental conditions for the application of nitrosation and nitrosation with subsequent chelation were established. The proportions of reactants in each method and the instability constants for the products were determined. The nitroso derivatives and their chelates obey Beers law and their absorbances were used for the determination of acetaminophen and salicylamide in pharmaceutical formulations. The proposed methods gave more accurate results than the official methods.

Utility of π-acceptors in charge-transfer complexation of alkaloids: chloranilic acid as a spectrophotometric titrant in non-aqueous media

A spectrophotometric titration method is described for the determination of some alkaloids and their dosage forms using 0.005 M chloranilic acid solution in 1,4-dioxan as the titrant. The end-point is determined by measuring the change in absorbance of the sample at 535 nm. Quantitative recoveries with good reproducibility are reported for atropine, emetine, reserpine, strychnine, yohimbine and four dosage forms. The least-squares method for the end-point location in the spectrophotometric titration is also proposed.

Use of Second Derivative Spectrophotometry For the Determination of Certain Cephalosporins and Their Acid-Induced Degradation Products In Combination

Abstract Methods for determination of individual cephalosporins and their corresponding acid-induced degradation products are described, based upon second derivative spectrophotometry. Linear plots of D2[dbnd](d2A/dλ2) values with negligible intercept were obtained versus concentration in the range of 0.4–2.4 mg% for both intact and degraded cephalosporins. Kinetic investigation of the cephalosporins degradation proved that the proposed method is applicable to stability determinations Compared with the official method the assay results of the different cephaiosporins pharmaceutical preparations were of equal accuracy (t-test) and reproducibility (F-test).

Spectrophotometric determination of acetaminophen, salicylamide and codeine phosphate in tablets

An accurate and simple method is proposed for the analysis of a three-component mixture composed of acetaminophen, salicylamide and codeine phosphate, without the necessity for the previous separation of any component. The first two components are determined directly by independent spectrophotometric measurements, based on the pH-induced spectral changes. Codeine phosphate is assayed by the formation of an ion pair with methyl orange. The procedure has been applied successfully to the analysis of known mixtures and commercial tablets.

Spectrophotometric assay of certain cardiovascular drugs through charge transfer reactions

Abstract Charge transfer reaction is described for the assay of certain cardiovascular drugs; carbochromen hydrochloride, verapamil hydrochloride, acebutolol hydrochloride, carazolol and propranolol hydrochloride. the three acceptors, p-chloranilic acid (p-CA), dichlorophenyl-indophenol (DCPIP) and 2,3-dichloro 5,6-dicyano p-benzoquinone (DDQ) have been used to carry out such assay. the reaction is based on the proton transfer from the p-CA to the drug base or electron transfer from the drug base to either DCPIP or DDQ and the subsequent possible formation of resonance hybrids of charge transfer complexes. Optimization of the reaction conditions has been investigated. Obediance to Beers law permitted the assay of these drugs in their dosage form. Calculating log e for different chromogens, the method sensitivity is decreasing in order of using DCPIP, DDQ & p-CA. the method has been compared with the traditional U.V. absorbance spectrophotometric method and found to be of equal accuracy (t-test) and equal...

Spectrofluorimetric assay of tetracycline and anhydrotetracycline in combination

Spectrofluorimetric methods are described for the assay of tetracycline (TC) and anhydrotetracycline (ATC) in combination, without prior separation. The interference from ATC in the TC assay has been corrected for by forming the aluminium complexes of both drugs and measuring the difference in fluorescence at 475 and 418 nm, with excitation at 393 nm. Similarly, measurement of the fluorescence of the magnesium complexes at 525 and 470 nm (excitation at 440 nm) nullifies TC interference in the ATC assay.

Spectrophotometric Assay of Fluphenazine HCL-Nortriptyline HCL Mixture in Tablets Using Fourier Function Method

Abstract The Fourier function method has been applied to the independent determination of fluphenazine hydrochloride (FH) and nortriptyline hydrochloride (KH) (1:20) in both laboratory made mixtures and commercial tablets. The method is based on the absorbance measurement of FE (the minor component) in concentrated mixture solutions, which is then properly diluted prior to NH absorbance measure-

Utility of Derivative Spectrophotometry in the Determination of Carbochromen Hydrochloride and Dipyridamole in the Presence of Their Oxidative Degradation Products

Abstract Direct spectrophotometric methods for the determination of carbochromen hydrochloride and dipyridamole, each in the presence of its oxidative degradation products, are presented. the methods are based on the first derivative (D1) and second derivative (D2) spectrophotometric measurement (absolute trough, U) at 336 nm and (Peak-trough, Y) at 309–342 nm for carbochromen hydrochloride and at 240–260 nm(U) and 246–268 nm(Y) for dipyridamole. Plots of D1 or D2 versus concentration were linear over the concentration range of 8.00–16.00 μg/ml for carbochromen hydrochloride and 4.00–12.00 μg/ml for dipyridamole. Oxidative degradation of these drugs has been optimized with respect to hydrogen peroxide concentration. Determining the intact in coexistence with its oxidative degradation product, the proposed derivative spectrophotometric methods proved to be of high potential in correcting the systematic error appearing in the results of the Amax method due to the latter. Assaying the commercial tablets, the...

Utility of Derivative Spectrophotometry For the Determination of Certain Cephalosporins and Their Alkali-Induced Degradation Products In Combination

Abstract First (D1-) and second (D2-) derivative spectrophotometric methods have been proposed for the assay of 7 cephalosporins, each with its alkali-induced degradation product in combination. Solutions of these cephalosporins in McIlvaines citric acid-phosphate buffer pH 7.0 were analyzed by measuring the 1st and 2nd derivative spectral response at certain wavelengths where the respective degradation products exhibit no contribution. the latter could be determined at the selected λ in the vicinity of negligible absorbance of the corresponding intact drug. Kinetic investigation of the alkaline degradation rate of cephalosporins revealed that the proposed methods were stability indicating. the different cephalosporin pharmaceutical preparations were assayed and gave results of equal accuracy (t-test)& reproducibility (F-test) with the corresponding official method of assay.

An Interactive Computer Program for Multicomponent Spectrophotometric Analysis Using Orthogonal Polynomials

Abstract A generalized interactive computer program (CNVSPI) is presented that enables the analyst to apply several methods for multicomponent analysis using conventional absorbance as well as orthogonal polynomials coefficients. The program performs the following: (i) stores data collected from spectrophotometer, (ii) processes data already stored in a file which include convolution with orthogonal polynomials, solving simultaneous linear equations and applying the least squares principle and (iii) displays data on screen, printer and plotter. Using that program multicomponent spectrophotometric methods have been applied to assay four component mixture in different matrices.