Magda H. Barary

Spectrophotometric determination of aldehydes in alcohols

A simple and sensitive method was described for the determination of formaldehyde and acetaldehyde in methanol and ethanol, respectively. A limit for aldehydes in alcohols is a necessary requiremen...

Determination of Some Cephalosporins Using Derivative Spectrophotometry

Abstract A rapid and simple method for the determination of cephalexin, cephalothin sodium and cephradin without prior separation from their alkali-induced degradation products is presented. By measuring the values of the first and second derivative spectra at certain wavelengths, the concentration of the intact drug can be calculated directly without interference of degradation products. The method was proved using synthetic mixtures of the intact drugs with their degradation products, and its suitability to monitor the stability of the drugs was demonstrated.

Simultaneous determination of tenoxicam and 2-aminopyridine using derivative spectrophotometry and high-performance liquid chromatography

Derivative spectrophotometry and high-performance liquid chromatography (HPLC) were used to determine tenoxicam and one of its decomposition products (2-aminopyridine) simultaneously and in the presence of each other. The derivative procedure was based on the linear relationship between the tenoxicam concentration and the second derivative amplitudes at 390-348 nm (peak-to-trough) measurement. The 2-aminopyridine was determined through measuring the second derivative amplitude at 241 nm (zero-crossing for tenoxicam). For the HPLC procedure, a reversed-phase C8 column with a mobile phase composed of 0.02 M sodium acetate-methanol-acetonitrile (11:8:1) with 0.005 M heptane sulfonic acid sodium salt, as an ion pair, was used to separate both compounds with 2,4-dinitrochlorobenzene, as an internal standard, in reasonable time. The flow rate was 1.5 ml min-1 with a programmable ultraviolet (UV) detection at 300 and 375 nm. Both UV derivative spectrophotometric and HPLC approaches were followed for confirming the purity of tenoxicam in bulk and tablets dosage form.

Derivative spectrophotometric analysis of two-component mixtures using a compensation technique

A method based on the compensation technique is presented for the derivative spectrophotometric determination of binary mixtures with overlapping spectra. By using ratios of the derivative maxima, the exact compensation of either component in the mixture can be achieved, followed by its determination. The personal judgement of the correct evaluation of the balance point is eliminated. The results obtained were precise and accurate.

Adsorptive stripping voltammetric behaviour of azomethine group in pyrimidine-containing drugs.

The stripping voltammetric behaviour of buspirone hydrochloride (BUS) and piribedil (PIR), as models of pyrimidine-containing compounds, was studied using a hanging mercury drop electrode (HMDE). A sensitive adsorptive stripping voltammetric method for determination of such drugs is described. The voltammetric peaks were obtained at -1.23 and -1.22 V for BUS and PIR. respectively, which correspond to the reduction of the azomethine group of pyrimidine ring in Britton-Robinson buffer (pH 7). Factors such as pH of supporting electrolyte, accumulation potential and time and instrumental parameters were optimized. Calibration plots and regression data validation, accuracy, precision, limits of detection, limits of quantification, and other aspects of analytical merit are presented. The applicability of the method was evaluated through determination of BUS and PIR in tablet dosage forms. A preliminary study of the analysis of plasma samples, spiked with the investigated drug, after a simple extraction procedure is described.

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...

Spectrophotometric determination of chlorpheniramine maleate and chlor-phenoxamine hydrochloride each in presence of caffeine as binary mixtures.

AbstractThe dye-salt formation method was successfully applied to the determination of chlorpheniramine maleate and chlorphenoxamine hydrochloride each in presence of caffeine. At pH 5, the chromogens (λmax=420 nm) produced with methyl orange in chloroform obeyed Beers law over the range 5-15 ug/ml and with relative SD less than 1%.

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 Determination of Bisacodyl and Piribedil

ABSTRACT Simple spectrophotometric methods are described for the assay of bisacodyl (BIS) and piribedil (PIR) based on charge‐transfer and ion‐pair complexation reactions. The first method is based on the reaction of the cited drugs with p‐chloranilic acid (p‐CA) in acetonitrile. The purple colored chromogen formed shows maximum absorbance at 518 nm. The second method is concerned with the reaction of the investigated drugs with picric acid (PA) and four sulphonphthalein acid dyes, namely; bromocresol green (BCG), bromocresol purple (BCP), bromophenol blue (BPB) and thymol blue (TB). The yellow ion‐pair complexes formed show absorption spectra with maxima within the range from 400 to 415 nm. The stoichiometric ratio was found to be 1:1, for all complexation reactions examined, as calculated by the continuous variations method. 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 applied for the determination of the analytes in their pure forms and in pharmaceutical preparations. The results were in good agreement with those obtained by the official and reported methods.

Sensitive spectrofluorimetric and spectrophotometric methods for the determination of thonzylamine hydrochloride in pharmaceutical preparations based on coupling with dimethylbarbituric acid in presence of dicyclohexylcarbodiimide

Two sensitive and selective spectrophotometric and spectrofluoimetric procedures were developed for the determination of thonzylamine hydrochloride (THAH) in tablets and nasal drops. The methods are based on König reaction which resulted in an orange-yellow fluorescent product. The orange-yellow product of the interaction between the dicyclohexylcarbodiimide (DCC), THAH and dimethylbarbituric acid (DMBA) showed an absorption maximum at 492 nm, a first-derivative signal at 494 nm and a fluorescence emission peak at 518 nm (lambda(ex)=492 nm). The orange-yellow color was found to be stable for at least 2 h. The reaction conditions were studied and optimized. The reaction obeys Beers law over the ranges 8-20 and 0.2-2.0 microg ml(-1) for the derivative spectrophotometric and fluorimetric measurements, respectively. The detection limits were found to be 0.29 and 0.018 microg ml(-1) for the spectrophotometric and fluorimetric measurements, respectively. The proposed methods were applied to the analysis of pharmaceutical formulations containing THAH, either alone or in combination with naphazoline nitrate.