Novel Selective Spectrophotometric Methods For The Determination Of Methimazole In Pure Form And In Pharmaceutical Formulation

Objective: To develop and validate new, selective spectrophotometric colorimetric analytical methods for the quantification of methimazole in its pure form and in its pharmaceutical preparations. Methods: Method A is based on the oxidation of methimazole with potassium permanganate in alkaline medium, the manganate ion produced was measured at λmax= 610 nm. Method B is a kinetic determination of methimazole using fixed-time method based on the oxidation of methimazole using known excess of cerium (IV) nitrate in acidic medium and assessing the unreacted Ce (IV) by adding a fixed amount of methyl orange and measuring the absorbance of the resultant solution at λmax=507 nm which is equivalent to the unreacted methyl orange. The reaction conditions and analytical parameters are investigated and optimized. Method validation was carried out according to ICH guidelines in terms of linearity, LOD, LOQ, precision, and accuracy. Results: Beer’s law is obeyed in the range of 1.50–15.00 μg/ml for method A and 0.25–3.00 μg/ml for method B. The developed methods were subjected to the detailed validation procedure. The proposed spectrophotometric methods were applied for the determination of the methimazole in its pure form and in its pharmaceutical formulation. The percentage recoveries were found to be 100.82 % and 99.85 % in the pharmaceutical formulation for the two proposed methods, respectively. Conclusion: Both developed spectrophotometric methods, considered as green analytical chemistry, were found to be novel, highly selective and can be applied for the quality control of methimazole in its pure form and in its pharmaceutical formulation based on the simplicity, applicability of the parameters, accessibility of the reagents employed and reasonably low time of analysis.

Extractive spectrophotometric methods for nebivolol hydrochloride.

Two simple and sensitive spectrophotometric methods have been developed for the estimation of Nebivolol hydrochloride in pure and pharmaceutical dosage forms. Method 1 is based on Ion-association complex formation of the drug with (SBT λmax 515 nm). Method 2 is based on Ion-association complex formation of the drug reacts with (BTB λmax 410nm). These methods have been statistically evaluated and found to be precise and accurate.

Extractive spectrophotometric methods for the determination of fenofibrate.

Two simple and sensitive spectrophotometric methods have been developed for the estimation of fenofibrate in pure and pharmaceutical dosage forms. Method A and B are based on ion association complex formation of the drug with Methylene Blue and Saffranine respectively. Beers law is obeyed in the concentration range of 5-15 μg/ml (Method A) and 10-30μg/ml (Method B) with good correlation coefficients. These methods have been statistically evaluated and found to be precise and accurate.

Validation of new spectrophotometric methods for quantitative determination of 7-ADCA in pharmaceutical formulations.

Three simple, sensitive and accurate methods are described for the determination of 7-Amino deacetoxy cephalosporanic acid (7-ADCA) in bulk drug and in formulations. Methods Ma to Mc are based on Redox / complex formation reaction between 7-ADCA and ammonium Molybdate and sulphuric acid (AM/H2SO4) (Ma), Ferric chloride/ Ortho Phenonthraline (Fe+3/o-Phen)(Mb) and FeCl3/potassium Ferricyanide (Fe+3/K3Fe(CN)6) (Mc) solutions. The chromogen being extractable with chloroform could be measured quantitatively at 625 (Ma), 510 (Mb) and 740 nm (Mc). All variables were studied to optimize the reaction conditions. Regression analysis of Beer's Law plot showed good correlation in the concentration ranges 10-60 for Ma, 1.25-7.5 for Mb and 2.5-15 mg/ml for Mc. The calculated molar absorptivity values are 2.835 x 103, 2.277 x 104, and 1.715 x 104 L/mol/cm for Ma to Mc, respectively. The methods were successfully applied to the determination of 7- ADCA in formulations and the results tallied well with the label claim. The results were statistically compared with those of a literature method by applying the student’s t-test and F-test. No interference was observed from the concomitant substances normally added to preparations. The accuracy and validity of the methods were further ascertained by performing recovery experiments via standard-addition method.

Spectrophotometric determination of fluvoxamine as maleate by selective methods.

Simple, accurate and reproducible visible spectrophotometric methods for the assay of drug fluvoxamine as maleate were established based on the formation of oxidative coupling reaction between the corresponding drug, Brucine-NaIO4 and DCQC. The procedures described were applied successfully to the determination of the compound in their dosage forms. The results showed that the proposed procedures compared favorably with the reference methods and satisfactory sensitivity, accuracy and precision. The optical characteristics such as Beer’s law limits, molar absorptivity and sandell’s sensitivity are reported. Regression analysis using the method of least squares was made to evaluate the slope (b), intercept (a) and correlation coefficient (r) and standard error of estimation (Se) for the drug.

Avaliação de métodos espectrofotométricos para determinação de proteína em amostras de lagoas de estabilização / Evaluation of spectrophotometric methods for protein determination in waste stabilization ponds sample

Esta pesquisa teve como objetivo principal comparar cinco métodos espectrofotométricos para determinação de proteínas em amostras provenientes de estações de tratamento de efluentes sanitários. O intuito foi definir uma metodologia de aplicação rápida, fácil e confiável para este tipo de amostra. As lagoas de estabilização, como sistemas de tratamento biológico, têm como principais constituintes proteínas, carboidratos e lipídeos, mas também apresentam muitos compostos interferentes, como por exemplo, uréia, detergentes e compostos fenólicos, que podem prejudicar a quantificação de tais parâmetros. Os métodos analisados foram Lowry, Biureto, Bradford e Ácido bicinconínico. O método de Lowry mostrou-se mais adequado às características da amostra, com boa reprodutibilidade, reagente específico, custo moderado e ausência de substancias interferentes.

This research had as main objective to compare five spectrophotometric methods for protein determination in samples proceeding from sanitary effluent of treatment plant. Intention was to define a methodology that is of fast and easy and reliable application for this type of sample. The stabilization ponds, as systems of biological treatment, have as main constituent proteins, carbohydrates and lipids, but also they present many interfering composites, for example, phenolic urea, detergents and composites, that can harm the quantification of such parameters. The analyzed methods had been Lowry, Biuret, Bradford and Acid bicinconinic. The method of Lowry revealed more adequate to the characteristics of the sample, with good reproducibility, specific reagent, moderate cost and absence of interfering substance.