Spectrophotometric determination of tetracycline and oxytetracycline in pharmaceutical preparations.
ABSTRACT A simple, rapid and sensitive spectrophotometric procedure for the assay of tetracycline hydrochloride and oxytetracycline hydrochloride has been developed. 2,2-Diphenyl-l-picrylhydrazyl (DPH), an intensely violet-coloured stable free radical, is changed in colour on reaction with the antibiotics investigated. The decrease in the intensity of the violet colour is used to measure the concentration of the drug. All measurements are made at 520 nm on methanolic solutions of the drug and reagent, buffered at pH 6. Beer's law is obeyed in the concentration ranges 2.5-15 and 2.5-20 mug/ml for tetracycline and oxytetracycline respectively. The proposed method has been successfully applied to analysis of the bulk drugs and their pharmaceutical formulations.
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ABSTRACT: Problem statement: Several studies were carried out to develop and validate a simple, rapid and accurate spectrophotometric method for the analysis of tetracycline (TC) and oxytetracycline (OTC) in the pure form and in pharmaceutical dosage forms, despite the varieties of these analytical techniques, the literature revealed that no spectrophotometric method for determination of tetracycline and oxytetracycline using charge transfer complexation with chloranilic acid has been reported. Approach: In the present study, a new and simple spectrophotometric method is described for the determinations of tetracycline (TC) and oxytetracycline (OTC), the method is based on the molecular interaction between the tetracyclines and Chloranilic Acid (CA), to form a charge-transfer complex in which the drugs acts as n-donor and chloranilic acid as �-acceptor in acetonitrile. The spectra, various experimental parameters for the reaction, the stability of the complex and the validty of the method were investigated. Results: The formed complex was found to absorb maximally at 540nm, Beer's law is obeyed in the concentration ranges 2.5-30 μg mL-1 and 5.0-40 μg mL-1 for TC and OTC, respectively. The limits of detection (S/N = 3) were 0.40 μg mL -1 for tetracycline and 0.50 μg mL -1 for oxytetracycline. The molar ratio was found to be approximately 1:1, confirming that one molecule of tetracycline or oxytetracycline combines with one molecule of chloranilic acid. Conclusions and Recommendations: The proposed method was found to be rapid, accurate and sensitive and may be applied for estimation of named drugs in pharmaceutical dosage forms without interferences from the common additives encountered. Percentage recoveries ranged from 99.17%±0.95-100.38%±0.82. From the statistical analysis of the obtained results one can conclude that no significant difference between the proposed method and other official methods as evident from the t-test and variance ratio. These findings recommend the utility of the proposed method in the quality control analysis of TC and OTC in the pure form and pharmaceutical dosage forms.American journal of pharmacology and toxicology 01/2008; 3(3):212-218.
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ABSTRACT: It is established that mixed-valence ruthenium oxide-ruthenium cyanide deposited on a glassy carbon electrode surface possesses catalytic activity for oxidation of tetracycline antibiotics (tetracycline, oxytetracycline, doxycycline). The catalytic effect consists of a decrease in the potential of tetracycline oxidation by about 200 mV and in a multiple increase of the oxidation current. A method is proposed for determining tetracycline, oxytetracycline, and doxycycline using the electrocatalytic response of a chemically modified electrode with a RuO-RuCN film under batch and flow-injection analysis conditions. The catalytic current depends linearly on the concentration of tetracycline antibiotics from 5 mM to 0.5 µM and 50 nM under batch and flow-injection analysis conditions, respectively.Pharmaceutical Chemistry Journal 08/2008; 42(9):545-549. · 0.32 Impact Factor
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ABSTRACT: Potassium iodide was used as a homogeneous electrocatalyst for the oxidation of captopril. Cyclic voltammetry and chronoamperometry were used in kinetic studies. The diffusion coefficient and catalytic rate constant were calculated to be 4.94 × 10−5 cm2 s−1 and 1.87 × 103 M−1 s−1, respectively. Linear sweep voltammetry was applied to quantitative determination of captopril; a linear calibration curve was obtained in the range of 4.0–500 μM of captopril with a limit of detection of 0.84 μM and a sensitivity of 0.035 A M−1. The method was applied to the determination of the drug in its tablets and validation methods showed that the results were quite satisfactory.Journal of the Iranian Chemical Society 12/2012; 9(6). · 1.47 Impact Factor