Abstract

A determination method of aromatic amino acids such as trytophan (Trp), tyrosine (Tyr), and phenylalanine (Phe) using luminol-H2O2-Cu(II) system has been presented. In the presence of an aromatic amino acid, the enhanced chemiluminescence (CL) intensity of luminol-H2O2-Cu(II) system was obtained by forming a complex between Cu(II) and the amino acid. Based on the above phenomenon, a sensitive and fast determination of three aromatic amino acids was performed using the CL method in batch-type detection system. To optimize determination conditions, the kinetic influence of an aromatic amino acid on the luminol-H2O2-Cu(II) system and the effects of H2O2 and Cu(II) concentration, pH, and buffers were investigated. Under the optimized conditions, the calibration curve was linear over the range from 1.0 × 10−6 to 2.0 × 10−5 M for Trp,1.0 × 10−6 to 2.0 × 10−5 M for Try, and 2.0 × 10−6 to 2.0 × 10−5 M for Phe, respectively. In this range, reproducibility (RSD, n = 4) of Trp, Try, and Phe were 3.21%, 2.64%, and 2.48%, respectively. The limit of detection (3σ/s) was calculated to be 6.8 × 10−7 M for Trp, 5.7 × 10−7 M for Try, and 9.6 × 10−7 M for Phe.