Aqueous systems for liquid scintillation counting: Use of hydrotropes

Abstract

Liquid hydrotropic systems, i.e., mixtures of hydrotropes and water-forming hydrophilic and hydrophobic regions, allow the solubilization of organic scintillators in essentially aqueous media. Such systems were applied to liquid scintillation counting with 4-[4-(5-phenyloxazol-2-yl)benzeyl]morpholine as scintillator, a 2,5-diphenyloxazole (PPO) derivative that proved well-soluble in acidic hydrotrope systems. Its fluorescence properties were studied. Phenylalanine labeled with 3H or 14C was used to test counting. While 14C counting worked acceptably, 3H counting was comparatively inefficient, probably due to the short lifetime of β-particles in aqueous environments.