Electrochemical determination of tryptophan based on silicon dioxide nanopartilces modified carbon paste electrode

Silicon dioxide nanoparticles modified carbon paste electrode was fabricated and used for electrochemical investigation of tryptophan. Compared with the unmodified electrode, the peak current significantly increased. Experimental conditions for tryptophan determination were optimized. Linear relationship between the peak current and tryptophan concentration was obtained in the range of 1.0 x 10(-7)-5.0 x 10(-6) mol L-1 and 5.0 x 10(-6)-5.0 x 10(-5) mol L-1 with an estimated detection limit of 3.6 x 10(-8) mol L-1 (/ = 3). Tryptophan in pharmaceutical and human serum samples were successfully determined by the proposed method.