Direct detection of dissolution of 14C-labeled compounds into an oil phase by the fat scintillation proximity method.

Traditional analysis of the dissolution of lipophilic compounds from aqueous phase into oil is often hampered by the necessity to separate the receiver oil compartment from the aqueous phase. In order to avoid possible artefacts associated with additional separation methods, a procedure was developed to selectively detect the entry of a compound into the oil phase of a oil/water dispersion. When a combination of a primary and secondary scintillator was predissolved in the oil, and solid 14C-tetrahydrolipstatin was added, increasing signals from the same container were measured upon prolonged incubation. The data are consistent with the hypothesis that 14C-THL that has dissolved in the oil phase is essentially responsible for the measured signal. The obtained dissolution profiles of 14C-THL into oil match with parallel experiments using classical procedures.