In a xanthoproteic test, if the color of the substance changes to yellow after adding nitric acid, the substance is a

In a xanthoproteic test, if the color of the substance changes to yellow after adding nitric acid, the substance is a protein.

But, from what I was learning, I believe that it's hard to find a single protein as you would go through that test, so, you'd have to look very close and know what you're doing in order to find one.