The use of carbon paste electrode in the direct voltammetric determination of tryptophan in pharmaceutical formulations.

A simple, fast and sensitive method is proposed for Tryptophan (Trp) determination in pharmaceutical formulations containing other non-electroative aminoacids, vitamins and hydroxycobalamines. Optimized conditions for differential pulse voltammetry allowed the determination of Trp with detection limit of 1.7 microM in 2-30 mM linear dynamic range (n=7; r=0.999), at a bare, non-treated carbon paste electrode. Ascorbic acid interference was evaluated and eliminated by choosing a suitable baseline for determination of peak currents for Trp.