3-Acetyl-umbelliferone 50 mg

3-Acetyl-7-hydroxycoumarin

These lipoid indicators are also probes for phase transitions in lipid membranes and may register the detailed chemical structure of the polar head-group region or the packing density in lamellar lipid layers. The reported lipoid pH indicators have either high (> 9.5) or low (< 3.0) apparent pK values (pKa) on neutral lipid layers. This may be a draw-back for the use of these compounds in biological system.