Two derivative spectrophotometric determinations of indapamide in pharmaceutical dosage forms

Simple, fast and reliable derivative spectrophotometric methods were developed for determination of indapamide in bulk and pharmaceutical dosage forms. The solutions of standard and the sample were prepared in methanol. The quantitative determination of the drug was carried out using the first-derivative values measured at 252.8 nm (N = 6) and the second-derivative values measured at 260.4 nm (N = 9). Calibration graphs constructed at their wavelengths of determination were linear in the concentration range of indapamide using peak to zero 1.00-30.00 mug ml(-1) for first-derivative and 1.00-35.00 mug ml(-1) for second-derivative spectrophotometric method. The developed methods were successfully applied for the assay of pharmaceutical dosage forms which do not require any preliminary separation or treatment of the samples. The details of the statistical treatment of analytical data are also presented. The results obtained from two derivative spectrophotornetry were compared with a spectrophotometric method reported in literature and no significant difference was found statistically. (C) 2002 Elsevier Science B.V. All rights reserved

Spectrophotometric determination of enoxacin as ion-pairs with bromophenol blue and bromocresol purple in bulk and pharmaceutical dosage form

Three simple, accurate and sensitive spectrophotometric methods were developed for determination of enoxacin. The methods based on extraction of this drug into chloroform as ion pairs with sulphonphthalein dyes as bromophenol blue and bromocresol purple. The optimum conditions of the reactions were studied and optimized. The absorbance of yellow products was measured at 412 nm for enoxacin-bromophenol blue and 410 nm for enoxacin-bromocresol purple. Linearity ranges were found to be 2.0-20.0 mug ml(-1) for enoxacin-bromophenol blue and 0.77-17.62 mug ml(-1) for enoxacin-bromocresol purple. The detection limits were found to be 0.084 mug ml(-1) and 0.193 mug ml(-1) for enoxacin-bromophenol blue and enoxacin-bromocresol purple, respectively. The composition of the ion pairs was found 1:1 by Job's method. The developed methods were applied successfully for the determination of this drug in pharmaceutical preparation. The data obtained by developed methods were compared with the spectrophotometric method in literature. No differences were found statistically. (C) 2002 Elsevier Science B.V. All rights reserved

Application of bromophenol blue and bromocresol purple for the extractive-spectrophotometric determination of ofloxacin

Simple, rapid, and extractive spectrophotometric methods were developed for the determination of ofloxacin in bulk and pharmaceutical dosage form. These methods are based on the formation of yellow ion-pair complexes between the basic nitrogen of the drug and bromophenol blue and bromocresol purple as sulphonphthalein dyes in phthalate buffer pH 3.0 and pH 3.1, respectively. The formed complexes were extracted with chloroform and measured at 414 nm for ofloxacin-bromophenol blue and 408 nm for ofloxacin-bromocresol purple. The analytical parameters and their effects on the reported systems are investigated. The reactions were extremely rapid at room temperature and the absorbance values remains unchanged at 48 h for ofloxacin-bromophenol blue and 72 h for ofloxacin-bromocresol purple. Beer's law was obeyed in the ranges 0.87-17.35 and 0.58-14.46 mug mL(-1) for ofloxacin-bromophenol blue and ofloxacin-bromocresol purple, respectively. The composition of the ion pairs was found 1:1 by Job's method. The proposed methods have been applied successfully for the analysis of the drug bulk form and its dosage form. The results obtained by the proposed methods were compared and statistical analysis showed no significant difference between the proposed methods

Electrochemical characteristics of zafirlukast and its determination in pharmaceutical formulations by voltammetric methods

Simple, rapid, reliable and fully validated voltammetric methods were developed for the determination of zafirlukast in pharmaceutical formulations, based on its electrochemical reduction at a hanging mercury drop electrode. Its electrochemical behavior in borate buffer (pH 8.0) was investigated using cyclic voltammetry, linear sweep voltammetry and chronoamperometry. The linear sweep voltammetric study of zafirlukast was carried out using glassy carbon eletrode. A well-defined cathodic peak at -1326 mV without the adsorptive accumulation time and at -1312 mV with 20 s of accumulation time versus Ag/AgCI reference electrode in square-wave and square-wave adsorptive stripping voltammetric methods, respectively, was observed. The experimental and instrumental parameters affecting the peak cur-rent of zafirlukast were investigated and optimized for the zatirlukast determination. The detection limits of square-wave and square-wave adsorptive stripping voltammetric methods were 50 and 5 ng mL(-1) with R.S.D. of 6.79 and 5.72%, respectively. The methods showed good sensitivity, accuracy, precision, selectivity, robustness and ruggedness. The proposed methods were applied for the determination of zafirlukast in its pharmaceutical formulations. The results obtained from developed methods were compared with a spectrophotometric method reported in the literature and no significant difference was found statistically. (c) 2005 Elsevier B.V. All rights reserved

Differential pulse adsorptive stripping voltammetric determination of zafirlukast in pharmaceutical formulations

Zafirlukast is a competitive and selective leukotriene receptor antagonist, which is indicated for the prophylaxis and treatment of mild to moderate persistent and chronic asthma. A new, simple, and sensitive adsorptive stripping voltammetric method was developed for the determination of zafirlukast in pharmaceutical formulations. The analysis was performed in pH 8.0 of borate buffer. At a well-defined cathodic peak currents were measured with a hanging mercury drop electrode at -1232 mV with 20 s of accumulation time vs. Ag/AgCl reference electrode. The influence of several variables including supporting electrolyte, pH, accumulation potential, accumulation time, pulse amplitude, and scan rate on the adsorptive stripping response of zafirlukast were evaluated. The linear calibration range was 38.00-412.00 ng mL(-1). The detection and quantification limits were 15.00 ng mL(-1) and 38.00 ng mL(-1), respectively. The method was validated by evaluating validation parameters and applied for the determination of zafirlukast in its pharmaceutical formulations. The results obtained from developed method were compared with a spectrophotometric method reported in the literature and no significant difference was found statistically

Determination of piribedil in pharmaceutical formulations by micellar electrokinetic capillary chromatography

A fast and simple micellar electrokinetic capillary chromatographic method was developed for the analysis of piribedil in pharmaceutical formulations. The effects of buffer concentration, buffer pH, sodium dodecyl sulphate (SDS) concentration, organic modifier, applied voltage and injection time were investigated. Optimum results were obtained with a 50 mM borate buffer at pH 8.0 containing 50 mM SDS by using a fused silica capillary (50 mum internal diameter, 72 cm effective length). The sample was injected hydrodynamically for 4 s at 50 mbar pressure and the applied voltage was +30 kV. The detection wavelength was set at 205 nm. Diflunisal was used as an internal standard. The analysis was performed at 25 degreesC and the total run time was 14 min. The method was suitably validated with respect to linearity range, limit of detection and quantification, precision, accuracy, specificity and robustness. The linear calibration range was 5-100 mug mL(-1) and the limit of detection was determined as 1 mug mL(-1). The method developed was successfully applied to the determination of piribedil in pharmaceutical formulations. The results were compared with a spectrophotometric method reported in the literature and no significant difference was found statistically

Determination of nifedipine in human plasma by square wave adsorptive stripping voltammetry

A simple, sensitive and selective square-wave adsorptive stripping voltammetric method has been developed and validated for the determination of nifedipine (NIF) in plasma. The assay was performed after single extraction of NIF from alkalinised plasma into organic phase. The adsorption behaviour of NIF on a hanging mercury drop electrode (HMDE) was explored by square-wave and cyclic voltammetry. The drug was accumulated at HMDE and a well-defined peak was obtained at - 730 mV versus Ag/AgCl in borate buffer of pH 9.0 including 0.01 M KCI. The linear concentration range was 2.89 x 10(-9) M-3.61 X 10(-7) M (1.00-125.01 ng ml(-1)) when using 30 s accumulation time at - 300 mV. Limit of detection and limit of quantification were 1.21 x 10(-9) M (0.42 ng ml(-1)) and 2.89 x 10(-9) M (1.00 ng ml(-1)) respectively. The intra-day relative standard deviation (RSD) ranged from 1.93 to 4.12% at three concentrations and the inter-day RSDs varied from 2.53 to 6.68%. The method was applied, to the plasma of pregnant women suffering from pregnancy induced hypertension, for the determination of NIF. The percentage recoveries varied from 96.26 to 99.49%. It has been shown that NIF could be determined in the presence of its main metabolite (dehydronifedipine) by the developed method. (C) 2002 Elsevier Science B.V. All rights reserved

Application of micellar electrokinetic capillary chromatography for the determination of nifedipine and its degradation product in pharmaceutical preparations

A simple and rapid micellar electrokinetic capillary chromatographic (MEKC) method for the analysis of nifedipine (NIF) and its degradation product was developed and validated. The compounds were separated using a 100 mM borate buffer at pH 9.0 containing 15 mM sodium dodecyl sulphate (SDS) and 25% acetonitrile, applied voltage of 30 kV, at working temperature 30degreesC and fused silica capillary of 72 cm effective length. Hydrodynamic injection (50 mbar) was applied for 3 s. The detection wavelength was set at 236 nm. Nimodipine was used as internal standard (IS) to compensate for minor fluctuations of migration times. Under the optimum conditions NIF, nitroso analog of dehydronifedipine (NDNIF) (degradation product exposed to sunlight) and IS were well separated with in 9 min. The method was validated with respect to linearity range, limit of detection and quantitation, precision, accuracy, specificity, ruggedness, and robustness. The method exhibited low limit of detection as 0.5 mug mL(-1), wide linearity range of 2-100 mug mL(-1) and high efficiency 1 x 10(5) N/m for NIF. The method was applied to the tablet form of NIF containing pharmaceutical preparations. The data were compared with that of the differential pulse polarographic method mentioned in literature. No significant difference was found statistically