Saied Belal

Quantitative determination of some thiazole cephalosporins through complexation with palladium (II) chloride

A simple and sensitive spectrophotometric method has been developed for the determination of five cephalosporins namely cefpodoxime (CFPD), ceftizoxime (CTIZ), ceftazidime (CZD), ceftriaxone (CTRX), and cefixime (CXIM). This method is based on the formation of yellow to yellowish brown complex between palladium (II) chloride and the investigated cephalosporins in the presence of sodium lauryl sulphate (SLS) as surfactant. The reaction conditions were studied and optimized. The procedure was validated. For each drug, the composition of this complex as well as its stability constant were also investigated. The proposed method was used for the determination of the above-mentioned drugs in their commercial preparations. The results were compared statistically with either official or published methods and showed no significant difference between the two methods.

Use of Cerium (IV) in the Spectrophotometric and Spectrofluorimetric Determinations of Penicillins and Cephalosporins in Their Pharmaceutical Preparations

Abstract Spectrophotometric and spectrofluorimetric procedures for the quantitative determination of four penicillins [Amoxycillin (AMX), Bacampicillin (BAC), Piperacillin (PPN) and Sultamcillin (SULT)] and ten cephalosporins [Cefadroxil (CDL), Cefamandole nafate (MAN), Cefuroxime axetil or sodium (CFX), Cefaclor (CFCR), Ceftazidime (CZD), Ceftizoxime (CTIZ), Ceftriaxone (CTRX), Cefoperazone (CPZ), Cefixime (CXIM) and Cefpodoxime proxetil (CFPD)] are described. Both methods are based on the acidic oxidation of the antibiotics with cerium (IV) at elevated temperature. The effect of the reagent concentration, volume of the acid,and the heating temperature were studied to optimize the reaction conditions. Each antibiotic was determined by either measuring the absorbance difference at 317 nm or the cerous inherent fluorescence at 256 and 356 nm for excitation and emission wavelengths, respectively. The two procedures have been successfully applied to the assay of these antibiotics in their pharmaceutical dosage forms. The obtained results have been statistically compared with those obtained by the official methods.

Selective spectrofluorimetric determination of phenolic β-lactam antibiotics through the formation of their coumarin derivatives

A simple, sensitive and selective spectrofluorimetric procedure was developed for the determination of amoxycillin, cefadroxil and cefoperazone. The method is based on the reaction between these drugs and ethyl acetoacetate, in acidic medium, to give yellow fluorescent products with excitation wavelengths ranging from 401 to 467 nm and emission wavelengths ranging from 465 to 503 nm. The reaction conditions were studied and optimized. The reaction obeyed Beers law over the range of 10.0-20.0, 1.5-1.0 and 50.0-100.0 microg ml(-1) for amoxycillin, cefadroxil and cefoperazone, respectively. Interferences from other antibiotics, drugs and dosage forms additives, in capsules and vials dosage forms, were investigated. The proposed method was applied to the analysis of pharmaceutical formulations (capsules and vials) containing the above antibiotics, either alone or in combination with other antibiotics or drugs. The validity of the method was tested by the recovery studies of standard addition which were found to be satisfactory. The results of the proposed method demonstrated that the method is equally accurate, precise and reproducible as the official methods (USP XXIII) and those published for the non-official binary mixtures.

Spectrophotometric and polarographic determination of enalapril and lisinopril using 2,4-dinitrofluorobenzene

The reaction of enalapril maleate and lisinopril with 2,4-dinitrofluorobenzene has been used to form colored products and polarographically active derivatives. The different experimental conditions have been optimized. The proposed methods have been validated and applied to the determination of both drugs in their commercial tablets. The results have been statistically compared with those obtained using the official HPLC methods.

Spectrophotometric Determination of Etilefrine, Ritodrine, Isoxsuprine and Salbutamol by Nitration and Subsequent Meisenheimer Complex Formation

Abstract A simple and sensitive colorimetric method has been developed for the determination of four phenolic drugs, namely, etilefrine hydrochloride, ritodrine hydrochloride, isoxsuprine hydrochloride and salbutamol sulphate. The method is, mainly, based on the nitration of the drug molecule followed by the subsequent formation of meisenheimer complex with a nucleophilic reagent (acetone) in alkaline medium. The experimental conditions leading to optimum chromogen intensity and stability were carefully studied and incorporated in the general procedure. Under the proposed conditions, the method was applicable over the concentration range of 4.8–16 μg ml−1 for the four drugs. The suggested method was further applied for the determination of the studied drugs in bulk and pharmaceutical dosage forms. The results of the analysis were found to agree statistically with those obtained with either the official or the referee methods. The procedure is characterized by its simplicity with accuracy and precision.

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.

Spectrophotometric determination of some phenolic sympathomimetic drugs through reaction with 2,6-dihaloquinone chlorimides

A spectrophotometric procedure is described for the determination of three phenolic sympathomimetic drugs: etilefrine hydrochloride, prenalterol hydrochloride and ritodrine hydrochloride. The method involves the use of 2,6-dichloro- and 2,6-dibromoquinone chlorimides as chromogenic reagents. The phenolic drugs produce a blue color, peaking from 610 to 630 nm. The colors produced obey Beers law and are suitable for the quantitative determination of the named compounds. The molar ratios of the reactions were established and a proposal for the reaction pathway is given. The procedures described were applied successfully to the determination of the compounds in their dosage forms. The results showed that the proposed procedures compared favourably with the reference methods and satisfactory sensitivity, accuracy and precision (SD < 0.1 μg ml−1) were noted. Detection limits are typically 0.2–0.4 μg ml−1. Other advantages of the procedures are their simplicity and speed.

Utilization of carbon disulphide for the analytical determination of betahistine hydrochloride and captopril in their pharmaceutical preparations

Spectrophotometric, atomic absorption spectrometric and high performance liquid chromatographic (HPLC) procedures have been developed for the determination of betahistine hydrochloride and captopril. The three procedures are based on the reaction of the drugs with carbon disulphide in alkaline medium with the formation of the dithiocarbamate or the trithiocarbonate derivative of betahistine (BHT) and captopril (CAP), respectively, then subsequent chelation with divalent metals. The absorbance measurement of the formed chelates or of the metal moiety of chelates was used as the basis for the spectrophotometric and atomic absorption spectrometric determinations. The formed complexes have been used as pre-column derivatizing procedure for the HPLC determination of the two drugs. The different experimental conditions were optimized. The calibration graphs were linear over the applicable concentration ranges. The proposed procedures were applied successfully for the determination of the two investigated drugs in their tablets dosage form.

Spectrophotometric determination of some corticosteroid drugs through charge-transfer complexation

Two spectrophotometric procedures are presented for the determination of three commonly used corticosteroid drugs. The procedures are based on the formation of the phenylhydrazones of the corticosteroids, which were subsequenly subjected to a charge-transfer complexation reaction with either the σ-acceptor iodine or the π-acceptor chloranil. The molar combining ratio and the optimum assay conditions were studied. Application of these procedures to the assay of the corticosteroids in tablet form is described. The mean recoveries were 99.26 ± 0.86, 99.67 ± 0.64 and 99.72 ± 1.39% using iodine as the acceptor reagent and 99.5 ± 0.78, 99.64 ± 0.62 and 99.9 ± 0.78% using chloranil as the acceptor reagent for prednisone, prednisolone and dexamethasone, respectively. The results obtained compared favourably with those obtained by the BP method.

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.