There are several resources and papers for the type of analysis that you are looking at - but you have provided very little nformation on what type of compound you are working with to start with - that would help in suggestions - we work with phenolic compounds and they do flouresce under uv light and particular compound has its own unique color. If you have a idea of the class of compound you are woking with - put a search of the compound and flourescence or uv absorbance and you should have your particular molecule.

I also suggest scrapping off the spot from TLC plate - vortex in minimal amount of methanol, centrifuge and run a uv scan (190-300nm) n a spectrophotometer - that gives very good idea for identification looking at the nature of curve.

i have no targeted compounds as i want to conduct chemical profiling of my crude extracts and using long UV as one of the screening methods.i will try it then.thank you!

The short answer is no, the spectral maxima of a UV active compound is not sufficient to act as a unique identifier for a given unknown compound. Nor are UV maxima commonly obtained for the purposes of characterisation.

A good understanding of UV-vis spectroscopy may give you an approximate idea of the chromophore you are looking at but little inference can be made without structural information. Semi empirical systems such as the Fieser-Kuhn and Woodward-Fieser rules have been developed that allow approximate prediction of UVmax from known structures. However due to the multivariate nature of structural diversity it would not be possible to work in the reverse direction without having some idea of the possible structures.

I see now. i have understand the problem now. thank you very much sir Eric B.J. Harris for the complete explaination