Study of tetra-substituted amino aluminum phthalocyanine as a new red-region substrate for the fluorometric determination of peroxidase and hydrogen peroxide

This is a first report on a new promising red-region fluorescence substrate , tetra-substituted amino aluminum phthalocyanine, which displays an excita tion maximum at 610 nm and an emission maximum at 678 nm in strongly acidic medium. It has been synthesized and applied to the determination of traces of hydrogen peroxide and horseradish peroxidase (HRP). The steady-state ca talytic rate depends upon the enzyme and substrate concentrations, and the Michaelis-Menten parameters K-m and V-max are measured to be 2.82 x 10(-6) mol l(-1) and 6.0 x 10(-9) mol l(-1) s(-1), respectively. Under optimum con ditions, the calibration graph has a linear range of 0.0 to 3.94 x 10(-11) mol l(-1) HRP and 0.0 to 2.0 x 10(-7) mol l(-1) hydrogen peroxide, with 3 s igma detection limits of 5.9 x 10(-13) mol l(-1) HRP and 1.4 x 10(-9) mol l (-1) H2O2. By coupling with a glucose oxidase-catalyzed reaction, glucose i n human serum has been quantified and the results are in good agreement wit h those reported by a hospital laboratory. The proposed method can greatly decrease the interference that results from background fluorescence or scat tered light and has a high analytical sensitivity. (C) 2001 Elsevier Scienc e B.V. All rights reserved.