Electrochemical behavior and voltammetric determination of L-tryptophan and L-tyrosine using a glassy carbon electrode modified with single-walled carbon nanohorns

We report a simple method for the direct and quantitative determination of L-tryptophan (Trp) and L-tyrosine (Tyr) using a glassy carbon electrode (GCE) modified with single-walled carbon nanohorns (SWCNHs). The SWCNH modified GCE exhibits high electrocatalytic activity towards the oxidation of both Trp and Tyr. It shows a linear response to Trp between 0.5 and 50 mu M and to Tyr between 2 and 30 mu M. The detection limits for Trp and Tyr are 50 nM and 400 nM, respectively. In addition, the modified GCE displays good selectivity and good sensitivity, thus making it suitable for the determination of Trp and Tyr in spiked serum samples.