Not just always blue dye but can be caused by a different catalyst during the reaction. If you’re concerned then don’t just inject it, you could potentially kill yourself. Take the tiniest amount possible orally, if you have no adverse effects after 1 hour weigh out maybe 2-5mg then take that orally, wait 1 more hour, still no adverse effects then take an active dose orally. Testing drugs you’re uncertain about is always best done orally as the body has natural mechanisms for dealing with certain poisons, ie. vomiting.
Injecting something, much like vaping something, that you’re unsure about is a very bad idea, at least go the oral route until you can confirm it’s what you think it is.