Differential pulse adsorptive stripping voltammetric determination of nanomolar levels of methotrexate utilizing bismuth film modified electrodes

A highly sensitive methodology is proposed utilizing a bismuth film modified electrode (BiFE) for the determination of methotrexate (MTX) based upon differential pulse adsorptive stripping voltammetry. The voltammetric behavior of MTX has been studied using cyclic voltammetry comparing the BiFE fabricated via electrodeposition onto a copper substrate, and as a control, a bare copper substrate electrode has also been compared. Additionally the optimum parameters have been explored using the electrochemical technique differential pulse adsorptive stripping voltammetry (DPAdSV) for the analysis of MTX. Analytical characteristics of the BiFE were explored with calibration curves which are found to be linear for MTX concentrations over the range from 12 nM to 1650 nM with the limit of detection of 0.9 nM. The proposed methodology for sensing MTX in pharmaceutical formulations via this novel approach was found to present a 95% confidence level when compared with high-performance liquid chromatography (HPLC). This work is of importance as it reports a simple analytical methodology that has the potential for field implementation and provides extremely low detection levels and analytical ranges which are analytically useful and is a valuable alternative to replace previously used mercury based electrodes.