Study on fluorometric determination of hydrogen peroxide catalyzed by iron(III)-tetrasulfonato-phthalocyanine with thiamine hydrochloride as a substrate

Iron(III)-tetrasulfonatophthalocyanine(FeTSPc) has been used as a mimetic e nzyme in the determination of hydrogen peroxide with thiamine hydrochloride as a fluorogenic substrate. The determinations were carried out in both ac idic and basic environments, with different limits of detection and linear ranges. In acidic condition, the linear calibration graph was obtained from 5.0x10(-8) mol/L to 8.0x10(-6) mol/L, with a detection limit of 2.1x10(-8) mol/L H2O2 when Na2HPO4-citric buffer solution (pH 2.8) was used as the re action medium. It was also found that using one of the three polybasic carb oxylic acids such as citric acid, tartaric acid and malonic acid as the cat alytic reaction medium can lead to particularly sensitive systems, permitti ng a detection limit as low as 3.5x10(-9) mol/L H2O2; whereas in basic reac tion medium (Na2CO3-NaHCO3 buffer solution, pH = 10.0), the linear range of the calibration graph was from 5.0x10(-8) mol/L to 2.0x10(6) mol/L H2O2 wi th a detection limit of 1.4x10(-8) mol/L. The applicability of the method t o the determination of glucose in human serum was demonstrated by investiga ting the recovery of the known glucose added to human serum.