GAS-CHROMATOGRAPHY OF TRYPTOPHAN TOGETHER WITH OTHER AMINO-ACIDS IN HYDROCHLORIC-ACID HYDROLYSATES

The classical hydrolysis of proteins with hydrochloric acid using tryptamine [3-(2-aminoethyl)indole] as additive revealed that tryptophan can be measured without destruction together with other amino acids by gas chromatography. An extensive study was made to establish the optimum conditions for protein hydrolysis (time and temperature of hydrolysis, amount of tryptamine) and for the derivatization of amino acids. The amino acid contents (including tryptophan) of standard proteins such as lysozyme, bovine and human albumin, human γ-globulin, casein and α-chymotrypsin and protein matrices (meat and fish meals, sunflower) were determined, after hydrochloric acid hydrolysis (4 h, 145°C) in the presence of tryptamine, as N,O,(S)-trifluoroacetyl isobutyl esters with SE-30 as the stationary phase. The reproducibility of the measurements was 4.6% (relative standard deviation) or less. © 1990.