The invention relates to an enhancement solution for an assay technology using lanthanide ions or their chelates as labels and dissociative fluorescence enhancement as a tool for detection, wherein said enhancement solution comprises a &bgr;-dietone of formula I
1
wherein R
1
is an aryl, optionally mono- or multi-substituted, and R
2
is a straight or branched alkyl chain with 2 to 9 carbon atoms substituted with four or more fluorine atoms. The invention further relates to a bioaffinity assay using lanthanide ions or their chelates as labels and dissociative fluorescence enhancement as a tool for detection comprising the use of said enhancement solution.