Sensitive anodic voltammetric determination of methylergometrine maleate in bulk and pharmaceutical dosage forms using differential pulse voltammetry

The voltammetric oxidation behavior of methylergometrine maleate (MM) was investigated applying differential pulse voltammetry (DPV) at three different electrodes; pencil graphite (PGE), carbon paste (CPE) and glassy carbon (GCE) electrodes. Cyclic voltammetric analyses were performed to optimize the voltammetric conditions. MM cyclic voltammogram showed a well-defined anodic peak at around 740-780 mV using Britton Robinson buffer at pH 5.0 for PGE and GCE, and pH 6.0 for CPE. The oxidation process was shown to be completely irreversible and diffusion-controlled. Based on this study, a sensitive quantitative method was proposed for determination of MM in its pure and pharmaceutical dosage forms. Various experimental conditions were examined and optimized; including pH, type of supporting electrolyte, accumulation time, scan rate and electrode material. The results obtained were linear over the concentration ranges 0.10-1.00, 0.08-0.36 and 0.50-5.50 mu g/mL with a square of correlation coefficient (R-2) 0.9996, 0.9995 and 0.9994 at PGE, CPE and GCE, respectively. The method showed a minimum detectability (LOD) of 0.02, 0.008 and 0.14 mu g/mL and a limit of quantitation (LOQ) of 0.06, 0.02 and 0.42 mu g/mL at PGE, CPE and GCE, respectively. The method was validated and compared with the reference valid method. It revealed good accuracy and reproducible results. The anticipated voltammetric procedure has the advantage of being simple, precise, inexpensive and highly sensitive. (C) 2015 Elsevier B.V. All rights reserved.