RESUMO
Three simple spectrophotometric methods have been described for the assay of olanzapine in its pure and pharmaceutical formulations. The direct method (A) is based on the drug oxidation with excess of N-bromosuccinimide in acidic medium and the two indirect methods (B and C) are based on the oxidation of the drug with excess of N-bromosuccinimide and cerium(IV)sulfate, followed by the reaction of the unconsumed oxidants with celestine blue. The calibration graphs were linear over the range 10 - 120 microg mL(-1) (method A), 0.5 - 6.0 microg mL(-1) (method B) and 0.6 - 3.0 microg mL(-1) (method C). After validation, the proposed methods were successfully applied to assay of olanzapine in its commercial tablets with mean percentage recoveries of 101.23 +/- 0.10, 96 +/- 0.10 and 94 +/- 0.04%. The mechanism of olanzapine oxidation with N-bromosuccinimide was also proposed.
Assuntos
Bromosuccinimida/análise , Cério/análise , Química Farmacêutica/métodos , Oxigênio/química , Espectrofotometria/métodos , Sulfatos/análise , Benzodiazepinas/análise , Benzodiazepinas/química , Calibragem , Técnicas de Química Analítica/métodos , Modelos Químicos , Olanzapina , Oxidantes/química , Oxigênio/metabolismo , Preparações Farmacêuticas/química , Tecnologia Farmacêutica/métodos , Fatores de TempoRESUMO
A simple, sensitive, and selective method for determination of acetaminophen based on its oxidation using N-bromosuccinimide (NBS) to produce a highly fluorescent product. Optimization of reaction variables was carried out concerning NBS concentration, pH, temperature, reaction time, and stability time. Under optimal analytical conditions, the fluorescent intensity was measured at lambda emission. 442 nm (excitation at lambda 330 nm). The linearity range is 120-800 ng/mL with lower detection limit of 33.6 ng/mL acetaminophen. The method was applied successfully to the determination of the compound in pharmaceutical preparations, with average recovery of 100.3 +/- 2%. The method was also applied successfully to the determination of the drug in spiked plasma samples, with an average recovery of 101.2 +/- 1%. Interference effects of some compounds, present in combination with acetaminophen, were studied and the tolerance limits of these compounds were determined.
Assuntos
Acetaminofen/análise , Análise Química do Sangue/métodos , Bromosuccinimida/análise , Técnicas de Química Analítica/métodos , Espectrometria de Fluorescência/métodos , Aminofenóis/química , Analgésicos não Narcóticos/análise , Centrifugação , Formas de Dosagem , Relação Dose-Resposta a Droga , Concentração de Íons de Hidrogênio , Indicadores e Reagentes , Oxidantes/química , Preparações Farmacêuticas/análise , Reprodutibilidade dos Testes , Comprimidos , Temperatura , Fatores de TempoRESUMO
A chemiluminescent method for the determination of isoniazid is described. Method is based on the chemiluminescence (CL) generated during the oxidation of luminol by N-bromosuccinimide (NBS) and N-chlorosuccinimide (NCS) in alkaline medium. It was found that the isoniazid could greatly enhance this CL intensity when present in the luminol solution. Based on this observation, a new flow-injection CL method for the determination of isoniazid is proposed in this paper. The detection limits were 4 and 3 ng ml(-1) isoniazid for the NBS- and NCS-luminol CL systems, respectively. The relative CL intensity was linear with the isoniazid concentration in the range of 8-600 and 600-5000 ng ml(-1) for the NBS-luminol CL system, and 6-200 and 200-2000 ng ml(-1) for the NCS-luminol CL system. The results obtained for the assay of pharmaceutical preparations compared well with those obtained by the official method and demonstrated good accuracy and precision.
Assuntos
Bromosuccinimida/análise , Isoniazida/análise , Luminol/análise , Succinimidas/análise , Análise de Injeção de Fluxo/métodos , Medições LuminescentesRESUMO
Two simple and sensitive indirect spectrophotometric methods for the assay of propranolol hydrochloride (PPH) and piroxicam (PX) in pure and pharmaceutical formulations have been proposed. The methods are based on the oxidation of PPH by a known excess of standard N-bromosuccinimide (NBS) and PX by ceric ammonium sulfate (CAS) in an acidic medium followed by the reaction of excess oxidant with promethazine hydrochloride (PMH) and methdilazine hydrochloride (MDH) to yield red-colored products. The absorbance values decreased linearly with increasing concentration of the drugs. The systems obeyed Beer's law over the concentration ranges of 0.5 - 12.5 and 0.3 - 16.0 microg/ml for PPH, and 0.4 - 7.5 and 0.2 - 10 microg/ml for PX with PMH and MDH, respectively. Molar absorptivity values, as calculated from Beer's law data, were found to be 1.36 x 10(4) and 2.55 x 10(4) l mol(-1) cm(-1) for PPH, and 2.08 x 10(4) and 2.05 x 10(4) l mol(-1) cm(-1) for PX with PMH and MDH, respectively. The common excipients and additives did not interfere with their determinations. The proposed methods have been successfully applied to the determinations of PPH and PX in various dosage forms. The results obtained by the proposed methods compare favorably with those of official methods.
