Magda M. Ayad

Spectrophotometric and atomic absorption spectrometric determination of ramipril and perindopril through ternary complex formation with eosin and Cu(II)

Two sensitive, spectrophotometric and atomic absorption spectrometric procedures are developed for the determination of ramipril and perindopril. Both methods are based on the formation of a ternary complex, extractable with chloroform, between copper(II), eosin and the two cited drugs. Spectrophotometrically under the optimum condition, the ternary complexes showed an absorption maximum at 535 nm, with apparent molar absorptivities of 6.55 and 4.00 x 10(3) mol(-1) x cm(-1) and Sandells sensitivities of 5.80 x 10(-2) and 1.04 x 10(-1) microg x cm(-2) for perindopril and ramipril, respectively. The solution of ternary complex obeyed Beers law in concentration ranges 10-60 and 20-100 microg x ml(-1) for perindopril and ramipril, respectively. The proposed method was applied to the determination of the two cited drugs in pharmaceutical tablets. The atomic absorption spectrometric method, directly through the quantitative determination of copper content of the organic extract of the complex, was also investigated for the purpose of enhancing the sensitivity of the determination. The spectrophotometric and atomic absorption spectrometric procedures hold their accuracy and precision well when applied to the determination of ramipril and perindopril dosage forms.

Spectrophotometric and AAS determination of ramipril and enalapril through ternary complex formation.

Two sensitive, spectrophotometric and atomic absorption spectrometric procedures are developed for the determination of two antihypertensive agents (enalapril maleate and ramipril). The spectrophotometric procedures for the two cited drugs are based on ternary complex formation. The first ternary complex (copper(II), eosin, and enalapril) was estimated by two methods; the first depends on its extraction with chloroform measuring at 533.4 nm. Beers law was obeyed in concentration range from 56 to 112 microg ml(-1). The second method for the same complex depends on its direct measurement after addition of methylcellulose as surfactant at the pH value 5 at 558.8 nm. The concentration range is from 19 to 32 microg ml(-1). The second ternary complex (iron(III), thiocyanate, and ramipril) was extracted with methylene chloride, measuring at 436.6 nm, with a concentration range 60-132 microg ml(-1). The direct atomic absorption spectrometric method through the quantitative determination of copper or iron content of the complex was also investigated for the purpose of enhancing the sensitivity of the determination. The spectrophotometric and atomic absorption spectrometric procedures hold their accuracy and precision well when applied to the determination of ramipril and enalapril dosage forms.

Spectrophotometric and atomic absorption spectrometric determination of certain cephalosporins.

Two sensitive spectrophotometric and atomic absorption spectrometric procedures are developed for the determination of certain cephalosporins (cefotaxime sodium and cefuroxime sodium). The spectrophotometric methods are based on the charge-transfer complex formation between these drugs as n-donors and 7,7,8,8-tetracyanoquinodimethane (TCNQ) or p-chloranilic acid (p-CA) as pi-acceptors to give highly coloured complex species. The coloured products are measured spectrophotometrically at 838 and 529 nm for TCNQ and p-CA, respectively. Beers law is obeyed in a concentration range of 7.6-15.2 and 7.1-20.0 microg x ml(-1) with TCNQ, 95.0-427.5 and 89.0-400.5 microg x ml-1 with p-CA for cefotaxime sodium and cefuroxime sodium, respectively. The atomic absorption spectrometric methods are based on the reaction of the above cited drugs after their alkali-hydrolysis with silver nitrate or lead acetate in neutral aqueous medium. The formed precipitates are quantitatively determined directly or indirectly through the silver or lead content of the precipitate formed or the residual unreacted metal in the filtrate by atomic absorption spectroscopy. The optimum conditions for hydrolysis and precipitation have been carefully studied. Beers law is obeyed in a concentration range of 1.9-11.4 and 1.78-8.90 microg x ml(-1) with Ag(I), 14.2-57.0 and 13.3-53.4 microg x ml-1 with Pb(II) for cefotaxime sodium and cefuroxime sodium, respectively (for both direct and indirect procedures). The spectrophotometric and the atomic absorption spectrometric procedures hold well their accuracy and precision when applied to the analysis of cefotaxime sodium and cefuroxime sodium dosage forms.

Potentiometric determination of famotidine in pharmaceutical formulations.

Two new potentiometric methods for determination of famotidine in pure form and in its pharmaceutical tablet form are developed. In the first method, the construction of plasticised poly(vinyl chloride) (PVC) matrix-type famotidine ion-selective membrane electrode and its use in the potentiometric determination of famotidine in pharmaceutical preparations are described. It is based on the use of the ion-associate species, formed by famotidine cation and tetraphenyl borate (TPB) counterion. The electrode exhibited a linear response for 1 x 10(-3)-1 x 10(-5) M of famotidine solutions over the pH range 1-5 with an average recovery of 99.26% and mean standard deviation of 1.12%. Common organic and inorganic cations showed negligible interference. In the second method, the conditions for the oxidimetric titration of famotidine have been studied. The method depends on using lead(IV) acetate for oxidation of the thioether contained in famotidine. The titration takes place in presence of catalytic quantities of potassium bromide (KBr). Direct potentiometric determination of 1.75 x 10(-2) M famotidine solution showed an average recovery of 100.51% with a mean standard deviation of 1.26%. The two methods have been applied successfully to commercial tablet. The results obtained reveal good percentage recoveries, which are in good agreement with those obtained by the official methods.

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.

Stability Constants of Cu2+, Fe3+ ↦ Zr4+ Chelates of Ampicillin, Dopamine and α-Methyl L-Dopa in Aqueous Medium

Abstract Formation constants of chelates of ampicillin, dopamine, and α -methyl L-dopa with Cu 2+, Fe3+ and Zr4+ have been determined in aqueous medium at ionic strength of 0.1 M (KC1) using Calvin-Bjerrum technique as applied by Irving and Rossotti. Zirconium forms relatively more stable chelates with ampicillin as compared to copper and iron. However, in case of dopamine and α-methyl L-dopa the chelation with iron is the more stable. The order of stability of copper and iron is in agreement with the Irving-Villiems order. The mixed ligand chelates have been, also, investigated. The stability sequence has been found to be Cu2+ < Fe3+ < Zr4+

Spectrofluorimetric micro-determination of imidazoline derivatives using 1-dimethylaminonaphthalene-5-sulphonyl chloride.

A sensitive method is presented for the fluorimetric determination of imidazoline derivatives of pharmaceutical importance. The drugs, namely antazoline hydrochloride, tolazolin hydrochloride and xylometazoline hydrochloride, are reacted with 1-dimethylaminonaphthalene-5-sulphonyl chloride (dansyl chloride) to give highly fluorescent derivatives. The limit of determination is 1 µg ml–1 and the relative standard deviation is less than 2%. The proposed method has been applied to the determination of these drugs in the pure form and in pharmaceutical preparations.

Determination of certain antihistamines through ternary complex formation

Abstract Antihistamines, namely terfenadine and chlorphenoxamine hydrochloride, react with cobalt and toxiocyanate ions to give ternary complexes. These complexes are readily extractable in benzene to give a blue colour with maximum absorption at 625nm. which can be used for Quantitative spectrophotometric analysis. The mean recoveries for authentic samples of terfenadine and chlorphenoxamine hydrochloride were 99.9 ± 0.3 S.E. and 99.9 ± 0.3 respectively (P = 0.05). Alternatively, determination of cobalt content of the benzene extract via atomic absorption spectroscopy provides an indirect method for the determination of these antihistamines. The mean recoveries were 99.33 ± 0.3 and 99.19 ± 0.3 respectively. Both methods were applied to the analysis of pharmaceutical preparations, the results obtained agreed well with those obtained by official methods.

D.c. polarographic determination of certain aminoglycosides

A polarographic method for the quantitative determination of kanamycin, gentamicin and amikacin in a pure form or in pharmaceutical dosage forms has been developed. The method is based on the preparation of the polarographically active nitroso detivatives of these compounds and their polarographic behaviour in both alkaline and acidic media has been studied. The nitroso derivative of kanamycin exhibits one cathodic wave at –1.8 V in alkaline medium and one at –0.8 V in acidic medium. The nitroso derivative of gentamicin shows three well defined cathodic waves at –0.4, –0.8 and –1.4 V in basic medium and two waves at –0.8 and 1.4 V in acidic medium. The nitroso derivative of amikacin shows two cathodic waves at –0.8 and –1.4 V in basic medium and at –0.4 and –0.8 V in acidic medium. A rectilinear relationship exists between the diffusion current and concentration in the ranges 10–60, 10–80 and 10–60 mg-% for kanamycin, gentamycin and amikacin with average recoveries of 99.4 ± 1.4, 99.1 ± 0.95 and 99.7 ± 1.1%, respectively.

U. V. Derivative Spectrophotometric Determination of Chlorphenoxamine Hydrochloride in Combination with Unhydrous Caffeine

Abstract A rapid spectrophotometric method for the analysis of chlorphenoxamine hydrochloride in combination with unhydrous caffeine was described. The method is based on the determination of chlorphenoxamine hydrochloride by at 225 and 232 nm while unhydrous caffeine recorde zero at the same wave lengths. Unhydrous caffeine determined by at 256 and 283 nm which corresponding to zero reading for chlorphenoxamine hydrochloride.