Determination of strychnine in strychnos nux-vomica crude and detoxified seeds by voltammetric method using a carbon paste electrode incorporated with gold nanoparticles

A new method using a carbon paste electrode modified with gold nanoparticles (GNPs/CPE) was developed and validated for determination of strychnine (ST) in Strychnos nux-vomica seeds. The modified carbon paste electrode consists of 24 nm-diameter colloidal gold nanoparticles resulting in an electrode that exhibits a significant catalytic effect toward the electrochemical oxidation of ST in a 0.2 M Britton-Robinson buffer solution (pH 7.0). The peak current increases linearly with the ST concentration within the molar concentration ranges of 8.00 x 10(-6) to 3.50 x 10(-5) M and 3.50 x 10(-5) to 1.15 x 10(-3) M. The detection limit (signal to noise > 3) for ST was found to be 4.6 x 10(-7) M, respectively. In this work, voltammetric methods such as cyclic voltammetry, chronocoulometry and differential pulse voltammetry were used. The method was then successfully applied to the determination of ST in Strychnos nux-vomica crude and detoxified seeds