Do you have literature references about the use of fluorescein for the ORAC assay?
We are the first group who reported the use of fluorescein for  both water-soluble and fat-soluble antioxidants. Please feel free to request a copy of our peer-reviewed papers published in the Journal of Agricultural and Food Chemistry1,2,3.

1 Ou, B.; Hampsch-Woodill, M.; Prior, R. L. Development and validation of an improved oxygen radical oxygen assay using fluorescein as the fluorescent Probe. J. Agric.Food Chem. 2001, 49, 4619-4626.

2 Huang, D., Ou, B., Hampsch-Woodill, M. Development and validation of oxygen radical absorbance capacity assay for lipophilic antioxidants using randomly methylated beta-cyclodextrin as the solubility enhancer J. Agric.Food Chem. 2002, in press.

3 Huang, D., Ou, B., Hampsch-Woodill, M., Prior, RL Measurement of hydroxyl radical prevention capacity. J. Agric.Food Chem. 2002, in press