Optimal conditions and sample storage for the determination of H2O2 in marine waters by the scopoletin-horseradish peroxidase fluorometric method

The conditions presently in use for the fluorometric determination of H2O2 in marine waters, by reacting H2O2 with scopoletin in the presence of horse radish peroxidase (HRP) and measuring the quenching of the fluorescence int ensity of scopoletin, are not the optimal conditions. Under the optimized c onditions of a pH of 8.5-9.5, an excitation wavelength of 390 nm and an emi ssion wavelength of 460, the sensitivity of the method can be increased sig nificantly, by up to more than a factor of 3 and the variations in the sens itivity from sample to sample can be significantly reduced. Furthermore, th e samples need not be analyzed immediately after sample collection as prese ntly prescribed. After scopoletin and HRP have been added to a sample immed iately after sample collection, the sample may be stored at room temperatur e in the dark for up to four days before the quenched fluorescence intensit y of scopoletin is read. (C) 1999 Elsevier Science B.V. All rights reserved .