MicroScint™-E cocktail was developed for assays that require in-situ partitioning of the radionuclide-containing lipid phase from the aqueous phase in microplates. In this respect MicroScint™-E cocktail is suitable for extracting lipids or other non-polar compounds from the aqueous phase in such extraction assays. It enables direct counting of the samples after addition of the cocktail, because the label is preferentially taken up into the lipophilic cocktail. MicroScint™-E cocktail has an absolute, unquenched Tritium efficiency of approximately 50% when measured in a 24-well white polystyrene OptiPlate microplate.