Rapid and Sensitive Online Determination of Some Selective α1-Blockers by Flow Injection Analysis with Micelle-Enhanced Fluorescence Detection

Green micellar liquid chromatographic analysis of alfuzosin hydrochloride and sildenafil citrate in a binary mixture compared to classical RPLC with stability indicating studies

Two simple and validated chromatographic studies were performed for simultaneous estimation of sildenafil citrate and alfuzosin hydrochloride in bulk, pharmaceuticals, and in the presence of their main degradation products. Two systems of mobile phase were applied isocratically for their first chromatographic separation using conventional and micellar mobile phases. Methanol, acetonitrile, and 0.02 M potassium dihydrogen phosphate (43:14:43 v/v; pH 4.66) were pumped at 1.3 mL/min in method I. Meanwhile, method II was based on less hazardous micellar mobile phase of nonionic surfactant (0.005 M Brij-35 in water; pH 2.5 adjusted with 0.1% orthophosphoric acid) with a flow rate of 1 mL/min. Both methods were carried on C18 column and coupled with UV detection at 225 nm at ambient temperature. The first method was rectilinear over the concentration range of 5-62.5 μg/mL for both drugs, while the second method showed higher linearity ranges of 0.5-40, 2.5-62.5 μg/mL for alfuzosin hydrochloride and sildenafil citrate, respectively. The developed methods successfully enabled the quantification of the studied binary mixture in their tablets dosage form and evaluation their stabilities. Validation of the proposed methods according to ICH guidelines and system suitability were ascertained. Moreover, the applied methods were evaluated and compared from the perspective of green analytical chemistry, employing the National Environmental Methods Index, analytical Eco-Scale score, and Green Analytical Procedure Index, as three assessment tools.

An efficient spectrofluorimetric method adopts doxazosin, terazosin and alfuzosin coupling with orthophthalaldehyde: Application in human plasma

A new, selective and sensitive spectrofluorimetric method was designed for the quantitation of doxazosin (DOX), terazosin (TER) and alfuzosin (ALF) in their dosage forms and human plasma. The method adopts efficient derivatization of the studied drugs with ortho-phthalaldehyde (OPA), in the presence of 2-mercaptoethanol in borate buffer (pH9.7) to generate a highly fluorescent isoindole derivatives, which can strongly enhance the fluorescence intensities of the studied drugs, allowing their sensitive determination at 430nm after excitation at 337nm. The fluorescence-concentration plots were rectilinear over the ranges (10.0-400.0) ng/mL. Detection and quantification limits were found to be (0.52-3.88) and (1.59-11.76) ng/mL, respectively. The proposed method was validated according to ICH guidelines, and successfully applied for the determination of pharmaceutical preparations of the studied drugs. Moreover, the high sensitivity of the proposed method permits its successful application to the analysis of the studied drugs in spiked human plasma with % recovery (96.12±1.34-100.66±0.57, n=3). A proposal for the reaction mechanism was presented.

Recent advances in flow injection analysis

A dynamic development of methodologies of analytical flow injection measurements during four decades since their invention has reinforced the solid position of flow analysis in the arsenal of techniques and instrumentation of contemporary chemical analysis.