Biamperometric and Differential Pulse Polarographic Methods for the Assay of Nomifensine Maleate

Abstract

Biamperometric titration and differential pulse polarography (DPP) are described for the analysis of nomifensine maleate powder and commercial capsules (Merital -50 mg). The biamperometric method involved the titration in cold dil. electrometric detection of end point. The mean percent recoveries obtained were 100.0 t 0.87 and 99.2 0.95 for the authentic powder and capsules, respectively. The DPP method was performed by measuring the peak current, i , obtained from the recorded differential polarogram under constant 50mV modulation amplitude. The peak current was measured at the peak potential of -1.02 V on the dropping mercury electrode (DME) versus Ag/AgCl/KCl (sat.) reference electrode at pH 5.0 (acetate buffer). A linear relationship between peak current and concentration was demonstrated in the range 3 to 30pg m1-l. for the capsules was 103.1 + 1.26. R HC1 medium against 0.01 M -NaN02 and P The mean percent recovery 242 MOHAMED ET AL. Nomifensine, (8-amino-1,2,3,4-tetrahydro-2-methyl-4-phenyl isoquinoline) maleate is used as a psychodrug for the treatment of depression. Several chromatographic methods including thin layer, gas-liquid, and high performance liquid chromatographic were reported for the detection and quantitation of the drug and its metabolites in various body fluids. Other cited quantitative NH2 Nomifensine Maleate procedures are direct spectr~photometry~ and amperometric titration' using silicotungstic acid as titrant. In the present work, DPP and biamperornetry have been proposed for the quantitation of nomifensine maleate. The DPP method is based on the electrochemical activity of the maleate anion' whereas biarnperometry is based on the diazotization reaction of the aromatic primary amino group with nitrous acid. 'O"' attractive to use for determining low levels of the drug whereas the biamperometric method is suitable for routine quality control. The results of analysis obtained by the two methods have been compared; and furthermore, the merits and shortcomings of both methods have been discussed. The DPP method is sensitive and is therefore Downloaded by [New York University] at 14:31 03 July 2015 BIAMPEROMETRIC AND DIFFERENTIAL PULSE POLAROGRAPHIC METHODS EXPERIMENTAL 243 Apparatus For biamperometric titration : Metrohm Polarizer E585, a pair of platinum electrodes and a spot galvanometer model EDSPOT (WPA Ltd., Saffron Walden, England) were used. For the differential pulse polarography: of Polarecord unit 6 2 6 and stand model E505 was used. A combination of three electrodes, namely, an indicator dropping mercury electrode (DME), a reference Ag/AgCl/KCl (sat.) electrode and a platinum auxiliary electrode were employed. of 6 3 cm Hg. an acetate buffer of pH 5.0 (base electrolyte) at a frequency of one drop sec regulated by an electromagnetic knocker synchronized with the polarograph. Metrohm polarograph consisting The DME was operated under a constant corrected pressure The mercury flow rate was approximately 2.1 mg sec-' in -1 All polarographic measurements were conducted at room temper...