Synchronous Derivative Fluorimetric Determination of 3 Aromatic Amino Acids in Food

Synchronous derivative fluorimetry was proposed for the simultaneous determination of tryptophane, tyrosine and phenylalanine. It was found that the interferences were eliminated by setting at the synchronous derivative fluorescence characteristic wavelengths of 279 nm for the determination of tryptophane, 224 nm for tyrosine, 256 nm for phenylalanine, with wavelength differences (Δλ) of 55 nm, 70 nm and 25 nm respectively in the synchronous derivative fluorescence measurements. Linear relationships between values of derivative fluorescence intensity and concentration of the 3 amino acids were found in definite ranges, with detection limits (3s/k) of 6.3×10-9mol·L-1 for tryptophane, 1.6×10-8mol·L-1 for tyrosine and 4.0 ×10-7mol·L-1 for phenylalanine. The proposed method was applied to the determination of the 3 aromatic amino acids in samples of honey, goat milk powder and beer, giving values of recovery ranged from 92.3% to 103%.