I have a hard time understanding panel C. The legend implies that an enzymatic conversion would be presented. Thus, one would observe a change in fluorescence/in the fluorescence spectrum over time. At the least, one would expect to see two spectra: one for naphthol AS-MX phosphate, one for naphthol AS-MX. It is not clear, from what compound the represented spectra are derived. The two spectra represented where recorded in 64% and 73% dioxan). This does not contain information regarding an enzymatic conversion.
Furthermore, it is also not immediately clear for the reader, what relative fluorescence intensity means here. Relative to what?