It can certainly be fixed, and to my personal ‘satisfaction’ I suppose.
What I mean is, if you have contaminated your test with B12 and water then it’s no biggie and you can just go ahead and use it.
BUT, if there are pathogenic agents or foreign proteins in there, you will likely experience a reaction, severity dependant on the injected agent (obviously).
If it were me I would throw it. But since you apparently can’t do that (and you must really be operating on a budget if you have to resort to reusing barrels), then I would AT THE VERY LEAST vent the vial with a needle and put it in an oven for about 30 minutes at about 110 degrees centegrade.
The next ‘level of security’ I suppose would be to filter the contents into a new vial. Somehow I doubt you have the tools for that, seeing as you have to reuse syringes…
The baking alone will kill any bacteria, but will not remove foreign proteins like pollen, etc that may have been in the water supply.
As another precaution, once you have prepared your gear to your personal satisfaction, let it cool or whatever and inject a tiny amount into a muscle that is not covered by much fat (I’m thinking quads).
Inject only just deep enough to get the oil into the muscle, NOT all the way to the length of the needle.
Why? Well this will serve as a ‘litmus test’ of sorts. If it is contaminated and you get an infection or reaction, at least you can see it straight away (because it’s near the surface), plus if (god forbid) it needed abrading away, there wouldn’t be as much muscle to take with it, due to the shallow depth.
Finally, the small volume would mean only a small amount of pathogenic material, giving your immune system a strong advantage in resolving the problem.
Please don’t do this again, lol.
What is the chances of infection from particles if he follows what you said to the letter?
My sister works for a needle exchange and tells me stories of people using gawd knows what to inject rec-drugs. Things like mud puddle water to vodka to lemon juice. Then they use cigarette butt to filter there spoons with. She sees people with abscesses all the time. Cause some will inject IM instead of IV(no more visible veins). Some will have no signs accept track marks. Then they come in and sometimes they have open sores with puss and shit running out or spraying on the walls with blood and puss. Point is infections are a very nasty business.