Electro-oxidation and adsorptive stripping voltammetric determination of ephedrine and pseudoephedrine at carboxylated multi-walled carbon nanotube-modified electrode

Abstract

Carboxylated multi-walled carbon nanotubes (MWCNTs) were directly cast onto a glassy carbon electrode to fabricate a MWCNT-modified electrode. The modified electrode exhibited good promotion towards the electrochemical oxidation of ephedrine and pseudoephedrine with greatly enhanced peak currents. Adsorptive stripping voltammetry (AdSV) with accumulation at open circuit potential has been used for quantification of these alkaloids. The method was validated and linear over the concentration range of 1–100 μM for both ephedrine and pseudoephedrine. Under optimal experimental conditions, the limits of detection (based on 3σ) for ephedrine and pseudoephedrine were determined as 0.75 μM and 0.82 μM respectively. The proposed method was successfully applied to pseudoephedrine determination in the presence of acetaminophen or cetirizine. This method has also been used for the determination of pseudoephedrine in some pharmaceutical preparations. In addition the proposed method has been successfully used for determination of ephedrine in diluted urine as a real sample.