Spectrophotometric determination of rosuvastatin in pharmaceutical formulations using quinalizarin

ABSTRACT This work presents the development of a methodology based on the formation of a charge transfer complex between quinalizarin and rosuvastatin, allowing for the spectrophotometric determination of rosuvastatin at 579 nm. The factors involved in the sensitivity of the technique were studied (nature and proportion of the solvent, reaction time, pH of aqueous phase and quinalizarin concentration). The proposed spectrophotometric procedures were validated with respect to linearity, ranges, precision, accuracy, detection and quantification limits. Calibration curves of the formed color products showed good linear relationships over the concentration range of 6-15 mg L-1. The proposed method has been successfully applied, which can be confirmed by interference test (comparison between the standard curves and addition of analyte), method precision (RSD 2.3% to 6 mg L-1), and by accuracy (statistically equivalent results between the proposed method and a chromatographic method of reference).

Avaliação da Atividade Antrópica no Rio Guaraguaçú (Pontal do Paraná, Paraná) / Assessment of Anthropic Activity in Rio Guaraguaçú (Pontal do Paraná, Paraná)

RESUMONesse trabalho são apresentados os resultados dos ensaios espectrofotométricos realizados nas amostras retiradas das águas do Rio Guaraguaçú localizado no litoral Paranaense. Esses ensaios foram realizados para quantificar o elemento fósforo pelo método do azul de molibdênio e o elemento nitrogênio pelos métodos de Griess e indofenol. Com esses resultados foi possível avaliar que o referido rio vem sofrendo com a atividade antrópica no seu entorno. Os resultados de fosfato estão acima dos valores estabelecidos pela Resolução 357/2005 do CONAMA, sendo que esses resultados, quando comparados com os obtidos em outro rio da região, são similares, daí observa-se que esse fato não é provocado por atividade antrópica. Já os resultados das concentrações dos íons amônio, nitrato e nitrito indicam que os valores obtidos estão abaixo dos valores máximos estabelecidos pela referida resolução, denota-se então que a presença desses dois últimos íons em águas superficiais ocorre onde a atividade antrópica está em expansão.

ABSTRACTIn this paper are present the results of spectrophotometric tests performed on water samples taken from the Guaraguaçú River located on the coast of Paraná State, Brazil. These tests were conducted to quantify the element phosphorus by the blue molybdenum method and the element nitrogen by Griess and indophenol methods. With these results it was possible to assess that this river has been suffering with anthropic activity in your surroundings. The results of phosphate are above the levels established in Resolution 357/2005 of CONAMA, and these results compared with those obtained in other river in the region are similar, hence we observe that this fact is not caused by human activity. Since the results of the concentrations of ammonium, nitrate and nitrite indicate that the values ​​obtained are below the maximums established by that resolution, then we denote that the presence of the latter two ions in surface water occurs where anthropic activity is expanding.

Title: Development of new spectrophotometric method for estimation of tenofovir disoproxil fumarate using MBTH reagent.

A new simple, sensitive and specific procedure has been developed for determination of tenofovir disoproxil fumarate in bulk and pharmaceutical dosage forms using MBTH reagent. The purpose of this analytical validation procedure is to validate it by laboratory experiments to prove that the method meets the minimum standards for laboratory use. 3-methyl-2-bezothiazoline hydrazone reacts with the secondary amine group of tenofovir in the presence of oxidizing agent, ferric chloride. The resulting apple green coloured chromogen when measured spectrophotometrically in visible region (i.e., 400-800nm) shows a maximum absorbance at 626.5nm. This method can be successfully applied for the determination of drug content in pharmaceutical formulations. The results of analysis have been validated statistically.

Development of new spectrophotometric method for estimation of tenofovir disoproxil fumarate using MBTH reagent.

A new simple, sensitive and specific procedure has been developed for determination of tenofovir disoproxil fumarate in bulk and pharmaceutical dosage forms using MBTH reagent. The purpose of this analytical validation procedure is to validate it by laboratory experiments to prove that the method meets the minimum standards for laboratory use. 3-methyl-2-bezothiazoline hydrazone reacts with the secondary amine group of tenofovir in the presence of oxidizing agent, ferric chloride. The resulting apple green coloured chromogen when measured spectrophotometrically in visible region (i.e., 400-800nm) shows a maximum absorbance at 626.5nm. This method can be successfully applied for the determination of drug content in pharmaceutical formulations. The results of analysis have been validated statistically.

Use of Hydrazine Carboxamide-2-[(2-Hydroxy-1- Naphthalenyl) Methylene] as an Analytical Reagent for the Extractive Spectrophotometric Determination of U(Vi).

Extraction and spectrophotometric determination of Uranium (VI) was carried out using Hydrazine Carboxamide-2-[(2-Hydroxy-1-Naphthalenyl) Methylene] as an analytical reagent. A reddish brown coloured complex is formed at pH 9.2 between U(VI):HCHNM which is extracted in n-butanol. An intense peak for the complex was observed at 385nm, well separated from that of ligand. Beer’s law is obeyed over the range of 2 to20 ppm. Composition of M:L in the complex was ascertained by Job’s method, mole ratio method and slope ratio method and found to be 1:2. Extraction and spectrophotometric determination of U(VI) was carried out using Hydrazine Carboxamide-2-[(2-Hydroxy-1- Naphthalenyl) Methylene] as an analytical reagent. A reddish brown coloured complex is formed at pH 9.2 between U(VI):HCHNM which is extracted in n-butanol. An intence peak for the complex was observed at 385nm, well separated from that of ligand. Beer’s law is obeyed over the range of 2 to 20 ppm. Composition of M:L in the complex was ascertained by Job’s method, mole ratio method and slope ratio method and found to be 1:2. Diverse ion effect was studied for various ions and the proposed method was found to be highly selective for the trace concentration of U(VI). Molar absorptivity and Sandell sensitivity values calculated are 0.1566 x104L mol-1cm-1 and 0.0585g/cm2 respectively. Proposed method has been successfully applied to analyse synthetic samples and the results were found to be in good agreement with standard gravimetric methods.

Development and validation of a simple spectrophotometric method for the determination of methyldopa in both bulk and marketed dosage formulations

A simple, precise, sensitive, rapid, specific and economical spectrophotometric method was developed to determine methyldopa (MTD) content in bulk and pharmaceutical dosage formulations. The proposed method was based on the formation of a colored product from the nitrosation reaction of MTD with sodium nitrite in an acid medium. The resultant nitroso derivative species reacts further with sodium hydroxide and is converted it into a more stable compound. This yellow nitrosation product exhibited an absorption maximum at 430 nm. Beer's Law was obeyed in a concentration range of 6.37 to 82.81 μg mL-1 MTD with an excellent coefficient of determination (R 2 = 0.9998). No interference was observed from common excipients in formulations. The results showed the method to be simple, accurate and readily applied for the determination of MTD in pure form and in pharmaceutical preparations. The analytical results obtained for these products using the proposed method are in agreement with those of the Brazilian Pharmacopoeia procedure at a 95% confidence level.

Desenvolveu-se método espectrofotométrico simples, preciso, sensível, rápido, específico e econômico para a determinação do teor de metildopa (MTD) em matéria-prima e em formulações farmacêuticas. O método proposto baseia-se na formação de um produto colorido resultante da reação de nitrosação da MTD com nitrito de sódio em meio ácido. A espécie resultante (nitroso derivado) reage com hidróxido de sódio e é convertida a um composto mais estável de cor amarela. Este produto exibiu máximo de absorção a 430 nm. A lei de Beer foi obedecida na faixa de concentração de 6,37 a 82,81 μg mL-1 de MTD com excelente coeficiente de determinação (R 2 = 0,9998). Não se observou interferência de excipientes comumente encontrados em formulações farmacêuticas comerciais. Os resultados demonstraram que o método proposto apresenta simplicidade, excelentes precisão e exatidão e pode ser aplicado para a determinação de MTD na sua forma pura e em preparações farmacêuticas. Os resultados analíticos obtidos pelo método proposto estão de acordo com aqueles obtidos pelo método oficial descrito na Farmacopéia Brasileira, a um nível de confiança de 95%.

Spectrophotometric Determination of Rabeprazole Sodium Using Two Charge Transfer Complexation Reactions.

This work presents two simple and direct spectrophotometric methods for determination of rabeprazole sodium (RB) through charge transfer complexation reactions. The first method is based on the reaction of the drug with p-chloranilic acid (p-CA) in acetonitrile to give a red colored product with maximum absorbance at 518 nm. The second method is based upon the interaction of RB and 7,7,8,8‐tetracyanoquinodimethane (TCNQ) in acetone resulting in the formation of a bluish-green complex measured at 845 nm. Factors affecting the color development were studied and optimized. The proposed colorimetric procedures were effectively validated with respect to linearity, ranges, precision, accuracy, robustness, detection and quantification limits. Regression analysis for the calibration curves of the formed color products with p-CA and TCNQ showed good linear relationships over the concentration ranges of 20–200 and 2–16 μg/mL respectively. The method was successfully applied to the assay of rabeprazole enteric coated tablets with good accuracy and precision. Assay results were statistically compared to a reference HPLC method where no significant differences were observed between the proposed methods and reference method.

Determinação espectrofotométrica de nitritos e nitratos em sais de cura / Spectrophotometric determination of nitrites and nitrates in curing salts

Foi aplicado um metodo espectrofotométrico para determinação de nitritos e nitratos de sódio em sais de cura. Baseia-se nas observações de Wetters & Uglum(1970)de que a razão entre as absorbâncias da solução aquoasa de nitrito de sódio a 355 e a 302 nm é constante e igual a 2,5 e que nitrato de sódio a não absorve 355nm, mas tem uma banda caracteristica a 302 nm. O fato de não haver interferência de íons cloreto nestas relações torna o processo apropriado ao controle analitico de nitrito em sais minerais de cura, simples, com a vantagem de ser direto. Trinta amostras conhecidas foram analisadas e os resultados, comparados aos obtidos pelos métodos clássicos, mostraram boa correlação (AU).

Determinação espectrofotométrica de eritomicina em medicamentos / Spectrophotometric determination of erythromycin in drugs

Neste trabalho foi descrito um metodo simples para a dosagem de eritromicina em medicamentos. O método envolve a determinação espectrofotométrica, a 540nm, do composto formado quando da reação da eritromicina com xantidrol em meio ácido. Estabeleceram-se as condições ideais para a reação e verificou-se a possibilidade de interferência de algumas substâncias que possam ser encontradadas em mistura com eritromicina em medicamentos. Testes de recuperação foram feitos. O erro do método é da ordem de 2%. Também foram estabecidas condições para separações e dosagem da eritromicina e seus sais, quando em mistura com teraciclina e espiramicina, por cromatografia em camada delgada (AU).

Caracteristica da buclizina e determinação por titulação espectrofotométrica em produtos farmacêuticos / Characteristics of buclizine and determination by spectrophotometric titration in pharmaceutical products

Descrevem-se neste artigo algumas características do dicloridrato de buclizina, um tranquilizante e anti-histamínico usado em, composição farmacêuticas. Curvas de titulação e espectros de absorção da substância pura são apresentados. Descreva-se, tambem, uma técnica para determinação da substância, quando livre, por simples titulação em meio não aquoso, com ácido perclórico e cristal violeta como indicador, e técnica para determinação por titulação espectrofotométrica, com ou sem purificação prévia por lavagem com éter dietílico, e por cromtografia em camada delgada e com leitura espectrifotométrica a 239nm, em solução clorofórmica, ou 274 nm, em bezeno (AU).

Pesquisa e determinação de mercurio em peixes de água salgada e doce do Brasil / Research and determination of mercury in saltwater and freshwater fish from Brazil

Descreve-se o método para determinação de residuos de mercúrio em peixes. Baseia-se na destruição da matéria orgânica com ácido sulfurico, ácido nítrico e catalizador á base de dióxido de titânio; extração do mercúrio em meio fortemente ácido com solução de ditizona em tetracloreto de carbono de carbono, e deternminação da absorbância em espectrofotômetro, a 490nm. Foi determinado o mercúrio residual em 10 amostras de peixes de água doce e 109 de água salgada, sendo que continham mercúrio 4 amostras no primeiro caso e no segundo, 27 amostras. A totalidade das amostras positivas e 50% da amostras negativas foram controladas por espectrofotometria de absorção atômica, havendo plena concordância nos resultados(AU).

SPECTROPHOTOMETRIC DETERMINATION OF VITAMIN E AND ITS SIGNIFICANCE / 营养学报

A modified rapid microprocedure for the determination of VE in serum, was described. VE reduced Fe3+ to Fe2+ and then the Fe2+ combined with bathophenanthroline to form a pink complex -which could be determined spect-rophotometrically. As little as 0.3ml (or 0.2ml) of serum or plasma sample was sufficient for determination. The reproducibility of this method was good. The CV was 4.1% (n=15). The recoveries of added VE (0.8, 0.2 and 1.6 mg/dl) were 86.3-102.5%. The mean value and SD of 99 normal adults were 1.15+ 0.31mg/dl. This spectrophotometric method was simple and could be used in common, laboratories. Some affecting frctors were discussed.