Analytical Sciences

Abstract − Analytical Sciences, 17(9), 1063 (2001).

Sensitive Determination of Dissolved Tryptophan in Freshwater by Alkaline Hydrolysis and HPLC
Fengchang WU*  and Eiichiro TANOUE**
*The State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Science, Guiyang, 550002, China
**Division of Earth and Environmental Sciences, Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8601, Japan
A sensitive method involving alkaline hydrolysis and HPLC analysis has been developed to detect nanomolar levels of tryptophan dissolved in freshwater. The procedure includes 1) alkaline hydrolysis with nitrogen atmosphere in Teflon-lined Pyrex tubes with 4.2 M sodium hydroxide at 110°C for 16 h, in which ascorbic acid was used as an antioxidant; 2) a determination step, in which tryptophan was separated efficiently from other amino acids by HPLC and measured by fluorescence. The mean recovery for tryptophan standard was 91.4% with an RSD of 3.3%. Using this method, dissolved tryptophan concentrations ranged from 10.91 to 41.83 nM in water samples from Lake Biwa, Japan.