After chromatographic separation of the mixture of different compounds obtained from a reaction I’ve got these highly fluorescent fractions. 

The first two test tube (on the right) contain compound A, the third tube contains the mixture of A and B and the rest contains compound B. Compound A is a highly fluorescent polyaromatic compound what was a side product of the reaction and even since there is only a few ten miligram in each solution, it causes a bright green fluorescence when lit with UV light.