Determination of tyrosine through a FIA-direct chemiluminescence procedure

A new FI-direct chemiluminescence method is proposed for the determination of tyrosine, based on the oxidation of the amino acid by K3Fe(CN)6 in potassium hydroxide medium, at room temperature and enhanced by the presence of β-cyclodextrin and formic acid. The dynamic range was linear over the range 1.0–10.0 mg l−1. A large study of the influence of foreign compounds was performed, including amino acids; and, the method showed high selectivity. The reproducibility between days resulted in a rsd (in slope%) of 4.8 and the repeatability with a rsd (n=50, 10.0 mg l−1) of 3.1%, the LOD (s/n=3) was 50 μg l−1 and sample throughput 98 h−1.