Quenching-Chemiluminescence Determination of Trace Amounts ofl-Tyrosine Contained in Dietary Supplement by Chemiluminescence Reaction of an Iron-Phthalocyanine Complex

The chemiluminescence (CL) signal immediately appeared when a hydrogen peroxide solution was injected into an iron-phthalocyanine tetrasulfonic acid (Fe-PTS) aqueous solution. Moreover, the CL intensity of Fe-PTS decreased by adding l -tyrosine. Based on these results, the determination of trace amounts of l -tyrosine was developed using the quenching-chemiluminescence. The calibration curve of l -tyrosine was obtained in the concentration range of 2.0 × 10 −7  M to 2.0 × 10 −5  M. Moreover, the relative standard deviation (RSD) was 1.63 % ( n = 5) for 2.0 × 10 −6  M l -tyrosine, and its detection limits (3 σ ) were 1.81 × 10 −7  M. The spike and recovery experiments for l -tyrosine were performed using a soft drink. Furthermore, the determination of l -tyrosine was applied to supplements containing various kinds of amino acids. Each satisfactory relative recovery was obtained at 98 to 102%.