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 K 3Fe(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.