You have struck it lucky, because DPPH is a free radical (unpaired, single electron) and has a lambda max at 517 no, i.e. is a purple solid and in solution.
Easy to detect on a tlc plate or column visually, UNLESS obscured by crud in the ginger extract.
I would suggest that you aim for an Rf value between 0.2 and 0.5 on the tlc plate; this will allow for other components of the extract to be separated from the DPPH.
Once you have isolated the DPPH, in several fractions, combine them, reduce the volume to concentrate and then re-analyze by tlc to check purity of DPPH; for this you will need a spray of 5% conc. H2SO4 in Ethanol and a hot plate or oven.
Other organic s will be charred to give brown/black spots.
Check the directory of your Chem Dept to see who, if anybody, deals with natural products.
Do some quick reading about DPPH and tlc/ column chromatography before you shoot over to their lab.
Everything is at your Google fingertips!