4. Conclusions
The FRET-based analytical method is sensitive and selective for
tryptophan with its reproducibility and rapidity greatly improved
after being incorporated in a flow-injection system. The system
can obtain both the information of tryptophan and total amino acid
content in less than 5 min, which was used to rapidly discriminate
soy sauces made by traditional fermentation process, acidhydrolysis
process or adulteration. The results showed a high
correlation with those obtained by a rapid capillary electrophoresis
protocol developed also in this work. Due to its selectivity and high
sensitivity, the present system may be used to rapidly detect tryptophan
content in urine, serum and other biomedical samples.