The invention relates to a simple continuous test for identifying structures that favour the arrangement of aromatics for charge-transfer complexes, e.g. complex phospholipid/lipid structures (bilayer, monolayer, aggregates, micelles), using synthetic fluorescence-marked acylglycerides, and to their use for determining the activity of lipases/lipase inhibitors, to a monoacylglyceride for use in this test and to a method for producing the same, to the substrate obtained therefrom and to a method for producing said substrate.