Electrochemical behavior and determination of tryptophan at the nafion and L-cysteine modified electrode

Nafion and Poly-cysteine modified glass carbon electrode(Nafion/L-cys/GCE)was constructed by electro-polymerization and dropping. The electrochemical behavior of tryptophan was investigated and the quantitative determination of tryptophan was performed by cyclic voltammetry(CV)and linear scanning voltammetry(LSV),respectively. The Nafion/L-cys/GCE displayed superior electrocatalytic activity towards the oxidation of Trp. Under the optimum experimental condition,the peak current of tryptophan was proportioned to its concentration in the range from 0.4×10^-6 to 40.0×10^-6 mol/L. The linear regression equation was I_pa(μA)=0.6997c(10^-6mol/L)+5.3(R²=0.9844)with detection limit of 1.0×10^-7 mol/L. The proposed method was successfully applied for the determination of Trp in fresh banana samples. The recovery was 95%~98%.