Figure 7. (A) Analysis of freshly prepared CN-Cbl standard (solid) and CN-Cbl standard exposed to light at room temperature for 30 min (dashed). Inset is a zoom view of 7–9 min for visualization of OH-Cbl changes. (B) Stability plot of relative CN-Cbl levels in light exposed CN-Cbl standard (open diamond), and media at 37 °C either protected from light (filled squares) or light exposed (open squares). (C) RP-UPLC chromatogram of light protected media (top), light exposed media (middle), and light exposed then KCN incubated media (bottom) at 37°C after 10 d.