Bray-Liebhafsky oscillatory reaction in a continuous-flow stirred tank reactor as the matrix system for determination of tyrosine

A kinetic method for the determination of l-tyrosine (Tyr) by analyte pulse perturbation, caused by different amounts of Tyr, in the Bray-Liebhafsky (BL) oscillatory reaction realized in a continuous-flow stirred tank reactor, is proposed. For such purposes, the BL oscillating reaction was kept in a stable non-equilibrium stationary state close to the bifurcation point and was used as the matrix reaction system. Under optimum reaction conditions, the linear relationship between the kinetic parameters, increment tau(2) (the period between first two oscillations that appear after applied perturbation) as well as tau(end) (the time elapsed between the perturbation of the BL reaction by Tyr and the termination of the oscillatory phase) and the Tyr concentrations is obtained over the ranges 1.1 x 10(-6) - 9.2 x 10(-6) mol L-1 and 1.1 x 10(-6) - 1.4 x 10(-5) mol L-1, with the limit of detections of 6.6 x 10(-7) mol L-1 and 6.4 x 10(-7) mol L-1. The described method that relies on a simple instrumental set-up, has been successfully applied to the determination of Tyr in a dietary supplement. Some aspects of the possible mechanism of Tyr action on the BL oscillator are discussed.