RESUMO
In this work, the possibility of simultaneous determination of three compounds with a single-injection step using batch injection analysis with multiple pulse amperometric detection (BIA-MPA) is demonstrated for the first time. A sequence of three potential pulses (+1.25 V, +1.60 V, and +1.80 V) was applied with the acquisition of three separate amperograms. 8-Chlorotheophylline was detected selectively at +1.25 V, both 8-chlorotheophylline and pyridoxine at +1.60V and 8-chlorotheophylline, pyridoxine, and diphenhydramine at +1.80 V. Subtraction between the currents detected at the three amperograms (with the help of correction factors) was used for the selective determination of pyridoxine and diphenhydramine. The proposed method is simple, inexpensive, fast (60 injections h(-1)), and present selectivity for the determination of the three compounds in pharmaceutical samples, with results similar to those obtained by HPLC (95% confidence level).
Assuntos
Eletroquímica/métodos , Injeções/métodos , Difenidramina/análise , Eletroquímica/economia , Concentração de Íons de Hidrogênio , Teofilina/análogos & derivados , Teofilina/análise , Fatores de TempoRESUMO
A high-performance capillary electrophoretic (CE) method has been developed for obtaining electropherograms of various extracts and the commercial formulation (fingerprints) of Hedera helix L used in Argentina as a cough's treatment. Also, a capillary zone electrophoresis (CZE) method was developed for the search, identification and determination of some possible adulterants. These likely adulterants are common synthetic drugs used in respiratory diseases (antitussive, decongestant and bronchodilator agents). Under optimum conditions, the analytes (ephedrine, codeine, diphenhydramine and constituents of H. helix formulations) were separated within less than 10 min in 20 mM sodium tetraborate buffer (pH 9.0). The present procedure was validated with respect to selectivity, linearity range, limits of detection (LOD) and quantification (LOQ), precision (repeatability and intermediate precision), solution stability and accuracy; the results obtained were satisfactory. Good linearity was obtained over two orders of magnitude and detection limits (S/N = 3) were better than 1.2 microg ml(-1) for all analytes. The CE methodology was successfully applied to the search and subsequent determination of ephedrine, codeine and diphenhydramine in H. helix extracts and its phytopharmaceutical products.
Assuntos
Hedera/química , Soluções Tampão , Química Farmacêutica , Codeína/análise , Difenidramina/análise , Contaminação de Medicamentos , Eletroforese Capilar , Efedrina/análise , Concentração de Íons de Hidrogênio , Extratos Vegetais/química , Reprodutibilidade dos TestesRESUMO
The present work describes a simple, accurate and rapid method for the separation and simultaneous determination of codeine, diphenhydramine, ephedrine and noscapine present in cough-cold syrup formulations by capillary zone electrophoresis. Factors affecting the separation were the buffer pH and concentration, applied voltage, and presence of additives. Separations were carried out in less than 10 min with a 20 mM sodium tetraborate buffer, pH 8.50. The carrier electrolyte gave baseline separation with good resolution, great reproducibility and accuracy. Calibration plots were linear over at least three orders of magnitude of analyte concentrations, the lower limits of detection being within the range 0.42-1.33 microg ml(-1). Detection was performed by UV absorbance at wavelengths of 205 and 250 nm. Quantification of the components in actual syrup formulations was calculated against the responses of freshly prepared external standard solutions. The method was validated and met all analysis requirements of quality assurance and quality control. The procedure was fast and reliable and commercial pharmaceuticals could be analyzed without prior sample clean-up procedure.
Assuntos
Antitussígenos/análise , Codeína/análise , Difenidramina/análise , Eletroforese Capilar/métodos , Efedrina/análise , Noscapina/análise , Concentração de Íons de Hidrogênio , Reprodutibilidade dos TestesRESUMO
A capillary zone electrophoresis (CZE) method has been developed to separate and quantitate naphazoline (NAPH), dyphenhydramine (DIP) and phenylephrine (PHE) in nasal solutions. Samples were diluted 1:25 in ultrapure water and injected at the anodic end. A central composite design has been used to optimise the experimental conditions for a complete and fast separation of the active ingredients studied. Critical parameters such as voltage, pH and buffer concentration have been studied to evaluate how they affect responses such as resolution and migration times. Separation was performed on a silica capillary with 75 microm I.D. and 70 cm total length at an applied voltage of 17.7 kV with a phosphate run buffer of pH 3.72 and 0.063 mol l(-1). Calibration curves were prepared for NAPH, DIP and PHE. For each analyte, the correlation coefficients were >0.999 (n=15). The RSD% of six replicate injections for each analyte were reasonably good. The method was applied to the quantitation of the three components in a commercial dosage form. The proposed method has the advantage of needing a very simple sample pretreatment and being faster than a typical HPLC chromatographic method.
Assuntos
Difenidramina/análise , Nafazolina/análise , Fenilefrina/análise , Administração Intranasal , Algoritmos , Eletroforese Capilar , Excipientes , Concentração de Íons de Hidrogênio , Indicadores e Reagentes , Soluções Farmacêuticas , Reprodutibilidade dos Testes , Espectrofotometria UltravioletaRESUMO
The separation of basic nitrogenous compounds commonly used as active ingredients in cold medicine formulations by micellar electrokinetic capillary chromatography and capillary zone electrophoresis with direct absorptiometric detection was investigated. The type and composition of the background electrolyte (BGE) were investigated with respect to separation selectivity and BGE stability. BGE of 10 mM sodium dihydrogenphosphate-sodium tetraborate buffer containing 10 mM SDS and 10% acetonitrile, pH 9.0 was found to be optimal. Dextromethorphan hydrobhromide, diphenhydramine hydrochloride and phenylephrine hydrochloride were baseline-separated in less than 11 min, giving separation efficiencies of up to 494,000 theoretical plates, reproducibility of corrected peaks areas below 3% relative standard deviation and concentration detection limits from 2.5 to 5.5 microg ml(-1). Detection was performed at 196 and 214 nm.
Assuntos
Dextrometorfano/análise , Difenidramina/análise , Expectorantes/análise , Descongestionantes Nasais/análise , Fenilefrina/análise , Química Farmacêutica , Dextrometorfano/química , Difenidramina/química , Eletroforese Capilar/métodos , Expectorantes/química , Descongestionantes Nasais/química , Fenilefrina/químicaRESUMO
The use of multivariate spectrophotometric calibration is reported for the analysis of two decongestant tablets, where paracetamol is the principal component and diphenhydramine or phenylpropanolamine are the minor components. The resolution of these mixtures has been accomplished without prior separation or derivatisation, by using partial least-squares (PLS-1) regression analysis of electronic absorption spectral data. Although the molar ratios of paracetamol to the minor components were 38:1 and 25:1 respectively, the latter have been determined with high accuracy and precision, and with no interference from tablet excipients. PLS is able to take into account small deviations of paracetamol from linearity in the studied concentration range. The application of classical least-squares (CLS) analysis yields unsatisfactory results, due to the low absorbances of the minor components within the range where all components obey Beer's law.