The electrochemical behavior and direct determination of tyrosine at a glassy carbon electrode modified with poly (9-aminoacridine)

9-aminoacridine was firstly immobilized on the surface of a glassy carbon electrode to form a poly (9-aminoacridine) film modified electrode. The results demonstrated that the modified electrode exhibited a high degree of catalytic activity towards the oxidation of tyrosine and can resolve the interference of tryptophan in the determination of tyrosine. Compared with the bare electrode, the peak current had obviously increased, and the peak potential had shifted in a negative direction. Under the optimum conditions, a linear response to tyrosine was observed in the concentration of 1.0x10(-6) -2.8x 10(-3) M, with a correlation coefficient of 0.9987, and a detection limit (S/N = 3) of 1.0x10(-7) M. The modified electrode has been successfully applied to determine the concentration of tyrosine in composite amino acid injections; and it displays excellent repeatability and high sensitivity. The proposed sensor has promising features such as ease of fabrication, good reproducibility, high stability and low cost. And most of all, it has good selectivity.