Spectrophotometric and potentiometric methods for the determination of cefprozil, dropropizine and tizanidine hydrochloride in pharmaceutical preparations

Two simple, accurate spectrophotometric and potentiometric methods were developed for the determination of cefprozil, dropropizine and tizanidine hydrochloride in their pharmaceutical preparations. The spectrophotometric method is based on the selective oxidation of cefprozil or tizanidine with N-bromosuccinimide in an alkaline medium to given an intense yellow product with a maximum absorption at 396 or 384 nm, respectively. The reaction conditions were studied and optimized. The reaction obeyed Beer's law over the concentration range 5-40 and 10-80 micro g mI[-1] for cefprozil and tizanidine hydrochloride, respectively. The potentiometric method involves the direct titration of cefprozil and dropropizine with N-bromosuccinimide in sulphuric acid medium and the end point is determined potentiometrically using platinum electrode. Cefprozil and dropropizine can be determined quantitatively in the concentration range of 0.13-1.30 and 0.118-1.180 mg with recovery values of 98.46-100.77 and 99.58-100.85% and relative standard deviations 0.39-0.54 and 0.52-0.87% for cefprozil and dropropizine, respectively. The proposed methods are applied for the determination of these drugs in pure forms and in pharmaceutical preparations

Physicochemical studies of complexes of some transition metal ions with rifampicin

From potentiometric equilibrium measurements of hydrogen-ion concentration at 25 and 35 with an ionic strength of 0.1 M [KCl] in 50% [v/v] aqueous methanol, the values of thermodynamic constants of rifampicin complexes with Co [II], Ni [II] Cu [II] and Zn [II] have been determined. Probable structures of the metal chelates are inferred from the elemental analysis, conductance measurements, IR and electronic spectra

Use of rose bengal in the colorimetric determination of some anti histamines

A precise colorimetric method is described for the estimation of phenyltoloxamine citrate, diphenyltoloxamine hydrochloride and chlorpheniramine maleate. The method depends on ion-pair extraction of association formed between tertiary amines and Rose Bengal [RB]. The reddish-purple ion associated formations were readily extractable in dichloromethane and exhibited maximum at 555 nm. The method obeys Beer's law in the concentration range 2-20 mug ml-1 for diphenylhydramine hydrochloride or chlorpheniramine maleate and 4-40 mug ml-1 for phenyltoloxamine citrate. Optimization of the experimental conditions is described. The proposed method was applied to the analysis of these drugs in pharmaceutical preparations, and results were in good agreement with those obtained by the BP or USP method

Spectrophotometric investigation of meto-clopramide and promazine palladium II complexes

The color reaction of metoclopramide or promazine and palladium [II] chloride has been investigated. The optimum reaction conditions, spectral characteristics, conditional stability constants and composition of the water-soluble complexes have been established. The structure of palladium [II] chelates in the solid state is also studied. A spectrophotometric method is proposed for the determination of metoclopramide and promazine hydrochlorides in pure forms and in pharmaceutical preparations. The method is simple, reproducible and accurate and is easily applied to the determination in tables and injection solutions

Extraction-spectrophotometric determination of prazosin hydrochloride with palladium [II]

The described spectrophotometric determination of prazosin hydrochloride [PZH] involves the extraction of the PZH-Pb [II] complex from an acetate buffer solution pH 6.0 into a chloroform layer. The absorbance of the extracted solution is measured at 420 nm. The molar absorptivity of the complex is 2.1 x 103 l mol-1 cm-1 at 420 nm. The effects of pH [4-10], Pb [II] chloride concentration and shaking time were studied. The ratio of prazosin molecules to palladium ions in the colored complex was found to be 1: 1. Finally, a procedure for the determination of PZH in pure form or in pharmaceutical preparations is recommended. The method is selective, sensitive and accurate

Spectrophotometric determination of imipramine and promazine through ion-pair formation with molybdenum [V] and thio-cyanate

A new procedure for determining imipramine and promazine by forming ion-pairs with molybdenum [V]-thiocyanate complex is studied. The method consists of extracting the ion-pair formed into dichloromethane from hydrochlorid acid medium which is orange-red in color. The ion- pair has an absorption maximum at 472 nm with molar absorptivities of 1.27 x 104 and 1.64 x 104 M mole-1 cm-1 for imipramine and promazine hydrochlorides, respectively. The ion-pair is stable for over one week at room temperature [25C]. Bent and French's method indicated 1: 4: 2 composition for molybdenum [V]-thiocyanate- imipramine or promazine ion-pair. The method obeys Beer's law in the concentration range 1.0-30.0 mug ml-1 of imipramine hydrochloride and 0.8-24.0 mug ml-1 of promazine hydrochloride. The proposed method can be applied to the determination of imipramine and promazine hydrochlorides in pharmaceutical preparations

Acid-base properties of 2,4-dihydroxy benzaldehyde-3 [6-phenyl] pyridazinyl hydrazone [DBP3H] formation constants of some of it's complexes

The objective of this study was to present some details of the synthesis, properties and the analytical behavior of the new reagent; namely, 2,4-dihydroxy-benzaldehyde-3 [6-phenyl] pyridazinyl hydrazone [DBPzH] and its possible applications for the determination and detection of some cations. The finding was based on the evaluation of the dissociation constant of the reagent, the composition and formation constants of the complexes by spectrophotometric and potentiometric methods

Spectrophotometric studies on determination of sulphadimidine

Spectrophotometric studies have been made for the determination of Sulfadimidine by reacting with some aldehydes, as salicylaldehyde and cinnamaldehyde. The color intensity of the formed Schiff bases was found to depend upon the nature and concentration of acid and aldehyde used. The optimum temperature for color development was 50C and heating time was 30 minutes. The procedures were developed for determination of sulfadimidine in presence of sulfanilamide, sulfaguanidine and sulfasomidine. The method has been successfully used for the spectrophotometric determination of sulfadimidine alone and in the presence of some sulfonamides

Atomic-absorption spectrophotometric determination of lead after extraction of lead fluorescence with Tri-n-butyl phosphate [TBP]

An atomic-absorption spectrophotometric method is used for the determination of trace amounts of lead by using the solvent extraction. The extraction of lead fluorescence with tri-n-butyl phosphate [TBP] and consequent atomic-absorption determination was found to decrease as the pyridine or cadmium ion concentration was increased, but it increased with the concentration of potassium iodide. Toluene, benzene and methyl ethyl ketone diluents increased the sensitivity of the method. Beer's law is obeyed in the concentration range 0.2 - 25 ppm of lead. Six replicate determinations on a sample containing 20 ppm of lead gave a mean absorbance of 0.85 with a standard deviation of 0.66%. The method was successfully applied to the determination of lead in blood serum

Thermodynamic studies on the complexes between transition metal ions and heterocyclic sulphonamides

Thermodynamic equilibrium constants have been determined by potentiometric titration at 20 degrees, 30 degrees, 40 degrees and 50 degrees for the reactions of sulfadiazine [1], sulfamerazine [2] and sulfasomidine [3] with Cu[11], Zn[11] Co[11], Ni[11], Mn[11] by the Irving and Rossotti method in 50% ethanol medium in order to compare the relative activities of different temperatures

Chelating tendencies of some sulpha drugs

The acid dissociation constant of sulfadiazine, sulfamerazine and sulfasomidine in 50% ethanolic solution were determined by pH-metric titration at temperature 30C and in different ionic strength. Also, their formation constants with Cu[II], Zn[II], Ni[II], Co[II], Mn[II] have been studied. The free energies of the complexes formed were deduced and the relation between the stabilities of these complexes and the ionization potenital of the cautions were discussed

Spectrophotometric determination of vanadium [V] with tannie acid and its application to biological fluids

Tannic acid is used in spectrophotometric determination of vanadium [V]. The reagent formed purple-blue color 1:1 complex with vanadium ion in the pH range 5-6, the wave length of maximum absorbence working wavelength, molar absorptivity, 1 mol-1, Sandell's sensitivity [in ug Cm-2] and standard deviation are: 332.2 nm; 8500; 0.028 and 0.52% respectively. The optimum working range is found to be from 0.2 to 10 ppm of vanadium. The stability constant and standard free energy of formation values are reported. The interference of several cations, anions, protein, peptone and some amino acids are investigated. Procedure for the elimination of such interference are suggested. The method has been used successfully for the determination of vanadium in biological fluids

Cephalexin complexes with some 3d transition-metal ions

The protonation constants of cephalexin and the stability constants of its complexes with Fe [III], Cu [II], Ni [II] and Mn [II] have been determined by pH-metric titration in aqueous medium at 30 and 40 and 0.1 M ionic strength [KCI]. The metal-ligand formation constants [long beta 2] calculated, show the order as Fe [III]> Cu [II]> Ni [III]> Mn [II]. Thermodynamic parameters [delta G, delta H and delta S] calculated at 30C and 0.1 M ionic strength, show that the interaction of cephalexin and these metal ions is chelation-reaction between ionic species. Thus, the entropy change plays important role in giving the observed stability