you can extracted with a proper solvent like slightly polar solvent  by solvent extraction  then you can make simple identification with TLC to know whether you have a single or mixture component. with FT-IR you can identify the presence of carbonyl group of the quinone. 

Please find attached papers. I hope these papers will be useful for your work

This can be isolated by careful steam distillation from commercially available Nigella sativa oil, as we have reported it: DOI: 10.1002/ciuz.201400660

This is for: Spät entdeckt: Thymochinin - Das Gelbe vom Öl, in:

S. Spiller, P. Mettke, H.-U. Siehl, K.-P. Zeller, D. Sicker, S. Berger

Chemie in Unserer Zeit, 2014, 48, 114-122.

The full preparative details are in the attachment of this paper(supporting info) which is available via internet.

Pay attention to a vigorous movement of the mixture and avoid an oily upper layer, this would cause a boiling delay. The thymoquinone is the yellow dyestuff in thisi yellow oil.

Awfully, I was not able to attach both files here. If you let me your e-mail address I could however send them, separately.