Determination of tryptophan in feeds and feed ingredients by high-performance liquid chromatography

Abstract

A high-performance liquid chromatographic procedure for the determination of tryptophan has been developed using the native fluorescence of the molecule as a means of detection. Proteins were hydrolysed with 6 M sodium hydroxide solution in the presence of maltodextrin, which has been demonstrated to prevent tryptophan degradation. Comparison of results from the proposed method with those from an existing procedure developed by Slump and Schreuder showed the two methods to be statistically equivalent. A wide range of feeds and feed ingredients were analysed, and the measured tryptophan levels were within the range expected from published data. The proposed method is rapid, sensitive and specific, and is recommended for routine laboratory use.