HPLC determination of tryptophan in foodstuffs using barium hydroxide hydrolysis at 140°C.

Hydrolysis of samples of food and feedstuffs with 2.7 N Ba(OH)2 at 140°C for 4 h was tested for the recovery of tryptophan. On the basis of 100% yield for the tryptophan content, corresponding to samples determined after 16h-hydrolysis at 125°C, the recovery averaged 98.7 ± 0.9% SD or 99.4 ± 2% depending on how the bulk or aliquot of hydrolysate was analysed (conventional or simplified procedure). Tryptophan can be assayed by high performance liquid chromatography and fluorescence detection within 8h, 4h-hydrolysis at 140°C and a simplified procedure.