The document discusses using different media to culture cells and measure yellow fluorescence over time. SC medium normally contains yellow fluorescent components. Cells were cultured in VD medium without riboflavin and their yellow fluorescence, peaking at 524nm, increased over time when excited at 430nm. The fluorescent material could pass through a dialysis membrane. A 3D fluorescent spectrum of the cell culture supernatant showed peaks from the excitation light. Using excitation between 500-525nm could avoid measuring yellow fluorescence from the supernatant.