CROCETIN, A WATER SOLUBLE CAROTENOID MONITOR FOR SINGLET MOLECULAR OXYGEN

Abstract
The water soluble carotenoid crocetin has been studied as a singlet molecular oxygen monitor in D2O solution, pD 8.4. Crocetin reacts chemically with singlet molecular oxygen with a rate constant of 4 x 108M‐1 s‐1. The rate constant for total quenching, chemical and physical, is 2.5 x 109M‐1 s‐1. Crocetin shows evidence for a reversible reaction with singlet molecular oxygen, as demonstrated by a fairly rapid absorption recovery after bleaching.