Analytical Sciences


Abstract − Analytical Sciences, 18(4), 417 (2002).

Selective Determination of Tryptophanby Using a Carbon Paste Electrode Modified with an Overoxidized PolypyrroleFilm
Zhidong CHEN, Kentaro OKAMURA, MisaHANAKI, and Tsutomu NAGAOKA 
Department of Applied Chemistry, Facultyof Engineering, Yamaguchi University, 2-16-1 Tokiwadai, Ube 755-8611,Japan
We report on the selective determination oftryptophan, using a carbon paste electrode coated with an overoxidizedpolypyrrole film. Out of 21 protein amino acids, only tryptophan andtyrosine exhibited an oxidative voltammetric response with this electrode.Tryptophan, which was preferentially concentrated to theelectrode under anopen circuit condition, was determined by the stripping voltammetrictechnique with a linear response range of 10 - 100 uM. For thedetermination of 10 uM tryptophan, interference from a 15-fold excess oftyrosine gave an positive error of 6%, while the other amino acids did notexhibit any detectable interference.