asperating blood or b12?

[JMan06]

i did an injection of prop npp and b12 into delt. .75cc prop .75ccnpp. .5cc b12

Since i shake a lot i like to asperate a couple times during injection to make sure. after the b12 went in and i continued with the other stuff (since b12 clumps together in barrel) i shook a bit so i asperated. red stuff came out. would this be the b12 or is it blood and how can you tell? I pulled out. I still gotta do the rest right now.

[fabry]

i think it is difficult that you aspirate back the b12 you injected... you should see small air bubbles coming up
also, when you aspirate blood i think the "pull" is very "smooth"...