Electrochemical investigation of tryptophan at gold nanoparticles modified electrode in the presence of sodium dodecylbenzene sulfonate

Glassy Carbon electrode modified with gold nanoparticles was prepared using electrodeposition at constant potential of -0.20 V, and characterized with scanning electron Microscopy and electrochemical techniques. Voltammetry was employed to study the electrochemical behaviors of tryptophan at the Au nanoparticles modified electrode in the presence of sodium dodecylbenzene sulfonate. The results showed that the Au nanoparticles modified electrode had good performance for the electrochemical oxidation of tryptophan. Compared with the unmodified electrode, the Au nanoparticles modified electrode improved the adsorption of tryptophan on the nanointerface and amplified its current response. The oxidation peak potential showed a negative shift of 50 mV in the presence of sodium dodecylbenzene sulfonate indicating that the electron transfer between the electrode and bulk solution of tryptophan was facilitated. Experimental parameters for tryptophan determination, such as deposition time, pH value, and accumulation conditions have been optimized. The oxidation peak current was linearly dependent on the tryptophan concentration and a calibration curve was obtained in the concentration range of 9.0 x 10(-8) mol L-1 to 5.0 x 10(-5) mol L-1 with detection limit of 8.0 x 10(-8) mol L-1 (S/N = 3). (C) 2009 Elsevier B.V. All rights reserved.