A few weeks ago I ordered 500 mg speed from GenieofGoodie, always measured my doses to 10mg, and was generally safe with it. I just got a marquis test kit so I could be safer in general and decided to test it. Put about 4-5 mg on white glass and put a drop on it, after 2-3 minutes there was still no color change. Looked up possible substances because it still works as an upper (I've never done speed previous to this so I could not compare the high), and the only possibilities are cocaine or caffeine.
DO NOT ORDER FROM HIM, HE IS FULL OF SHIT.
I doubt you would have any effect from 10mg of caffeine though. A regular cup of coffee contains up to 100mg and wakeup caffeine pills contain 200mg
Have you considered maybe it is a speedy type of research chemical that doesn't show up with the Marquis?