you should be good. the worst thing that I can see happening is maybe if the girl isn't the best product, that it might clog up the rig just a little bit. but I don't think the molecular structure will change at all like when leaving H around in a syringe
I don't think there'd be anything that would change the coke at all and make the high any different or dangerous. As kenaz mentioned though, you should definitely be worried about bacteria growing in there, especially if you just used anything but distilled or some sort of sterile water.
Doing this is definitely not advisable and by no means guaranteed to be safe at all, but if you're going to do this, store it somewhere cold and dark, think refrigerator. The colder and darker it is, the less chance the bacteria have to thrive.
Maybe someone a little more knowledgeable about storing solutions for injection could let me know if I might be right or not here, but I would imagine you could dilute some high proof alcohol, preferably vodka due to it's much greater filtration compared to other spirits, it would keep the solution sterile and if you dilute it enough, the ethanol shouldn't burn too badly when injected.
^^This is just a thought of mine and is by no means something you should think is a good idea to try.
^^Definitely. There's no way in hell that the solution is sterile even from the get go. There's a 99.99% chance that at some point it was placed on a table or something and mixed with cut in an unsterile environment. That's why I mentioned possibly using high proof alcohol to sterilize it and again preferably vodka due to it being filtered much more than any other spirit.
Do you have any thoughts on whether this would be sensible if you diluted the vodka to a reasonable point? Obviously it'd be best to get the type of preservatives used in medical solutions, like benzyl alcohol, but I suggested this due to the much easier availability of it and the possibility the OP has some laying around.
Wouldn't the ethanol fuck you up a lot when injetced though? Could be fun though; like super acute snorting and drinking.
I might also be concerned about the growth of bacteria and other microorganisms in the syringe. Even if the OP was using distilled water, I doubt the coke was sterile.