Chemometrics-assisted voltammetric determination of timolol maleate and brimonidine tartrate utilizing a carbon paste electrode modified with iron (III) oxide nanoparticles

A carbon paste electrode modified with iron (III) oxide nanoparticles (MCPE) was fabricated for the simultaneous quantitative voltammetric determination of timolol maleate (TM) and brimonidine tartrate (BT) using chemometrics analysis. In this paper, for the first time, a novel voltammetric method was developed for a rapid, sensitive and efficient simultaneous determination of TM and BT in the marketed ophthalmic formulation. This method is based on the incorporation of iron (III) oxide nanoparticles into the carbon paste electrode which improves the characteristics of the electrode and increases its sensitivity. The electrochemical oxidation of the two drugs was established using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and square wave voltammetry (SWV) techniques. DPV and SWV techniques were developed for the quantitative voltammetric determination of TM and BT in their pure forms and pharmaceutical formulations. The method revealed a minimum detectability (LOD) of 1.31 x 10(-6) mu g/mL for BT and 1.37 x 10(-5) mu g/mL for TM and a limit of quantitation (LOQ) of 3.97 x 10(-6) mu g/mL for BT and 4.16 x 10(-5) mu g/mL for TM for SWV. Different chemometric methods (PCR and PIS) were tested for the resolution of the overlapped peaks of both compounds and their determination in mixtures. The best results were obtained with the PIS method. The proposed method was validated and compared with the reported HPLC method, revealing the good accuracy, precision and reproducible results of this method.