Fig. 3.

Light-sensitive nature of MP Biomedicals and RR535 compounds (1-amino-5-naphthol-7-sulfonic acid). Photographic images of two sets of (a) MP Biomedicals and (b) RR535 compounds at concentrations of 0.5, 1.5, 5.0 and 15.0 mM in DMSO which were either stored in the dark (•) or on the bench top exposed to a twelve hour cycle of room light (☼) over a one week period. Light exposure resulted in darkening of both compounds relative to the matched sample sets which were stored in the dark. c Absorbance spectra from 400 to 700 nm of 0.86 mM concentrations of MP Biomedicals and d) RR535 that were either stored in the dark or exposed to room light for seven and seventeen days. Scans of each compound on the day they were prepared from solid compound are included for comparison, demonstrating the light- and time-dependent increase in absorbance of both compounds