In general, UV-VIS-NIR is not used for chemical identification, as
>>12775482says you essentially would need to compare it to a known spectrum (as opposed to something like XPS, which can give elemental composition).
Instead, UV-Vis-NIR is used to determine the concentration of solution, again by comparison to a standard, or used for photovoltaic active properties. For example, you can use the onset of absorption to give an estimate of the optical bandgap for semiconducting materials.
