Analytical applications of electrode sensitive to labetalol in pharmaceuticals

Abstract

The analytical properties of an ion-selective electrode sensitive to labetalol with a liquid membrane, based on ion-pair complexes with sodium tetraphenylborate (TPBNa + ) are described. The studied electrode can be used for the determination of labetalol hydrochloride as a protonated form of labetalol in pharmaceuticals. The calibration curve, e.g. EMF=f(pC LabHC l ) is linear in the range from 10 ¡5 to 10 ¡2 mol L ¡1 with a correlation coe¯cient of 0.9992 and slope of 61.13 mV/decade, which is close to the Nernstian slope. The detection limit of the examined electrode is 7.20£10 ¡6 mol L ¡1 . The in®uence of pH of the tested solutions on the formulation of the electrode is not as considerable since the electrode works correctly in the pH range 3.0-8.0. The main attributes of the developed electrode are: stability, good reproducibility of EMF and short response time, close to 30 seconds depending on labetalol concentration in the solution. The electrode shows good selectivity for many inorganic ions. The selectivity for drug cations is weaker due to the structural similarity of the interfering cations to labetalol. The results of labetalol determination using direct potentiometry in drugs such as Pressocard (Polpharma) and Trandate (GlaxoWellcome) were compatible with the quantity of labetalol declared by the manufacturer, and with parallel UV spectrophotometric and HPLC determinations.

Photocatalysis of ethanol oxidation by tetrachloroferrate(III) supported on Dowex 2‐X8

“…The data are consistent with a photooxidation process involving a hydroperoxide, as has been proposed for the oxidative photodecomposition of dichloromethane catalyzed by FeCl 4 − on Dowex and the oxidative photodecomposition of chloroform by homogeneous FeCl 4 − . As was proposed for those systems, the reaction can be expected to be initiated through photodissociation of a chlorine atom following excitation into a LMCT band . Hydrogen abstraction from the α‐carbon of the alcohol and the subsequent reaction of the hydroxyalkyl radical with oxygen yield a peroxy radical (R + is used to signify cation resin sites): …”

Spectrophotometric Determination of Labetalol and Lercanidipine in Pure Form and in Pharmaceutical Preparations Using Ferric-1,10-Phenanthroline

“…The therapeutic importance of LBT initiated several reports on its determination in formulations viz: spectrophotometry (4-7), spectrofluorimetry (8-13), HPLC (14)(15)(16)(17), HPLC-MS (18)(19)(20), capillary electrophoresis (21,22), and Voltammetry (23). LBT was also determined in pharmaceuticals using an ion selective electrode sensitive to LBT with a liquid membrane (24).…”

Electrochemical Quantitative Assessment of Labetalol Hydrochloride in Pure Form and Combined Pharmaceutical Formulations

“…[2][3][4] Literature survey revealed that various analytical techniques were employed to estimate the concentration of Lab in pharmaceutical preparations, either alone or in combination with hydrochlorothiazide, and in biological fluids. These techniques include spectrofluorimetry, [5][6][7][8][9][10] chromatography, [11][12][13][14][15][16][17][18] capillary electrophoresis, 19,20 capillary isotachophoresis, 21 NMR spectroscopy, 22 ion-selective electrode using ion-pair complex, 23 and adsorptive voltammetry, 24 methods which in comparison to proposed electrodes require sample manipulation, are affected by various interferences, inappropriate for colored or turbid solutions, and more expensive as they require sophisticated equipment and software for data processing.…”