Was it distilled water? tap water? Evian?
How cool was cool? cupboard? fridge? freezer?
was the vial sterilised beforehand?
as MrHH said above, did you add EtOH?
regarding the 2c-b, worst case it should not have degraded any amount that would be noticeable in effects.
If you have a microscope, glass petri dish/plate and good lighting you should check for any excessive clouding in a small sample of the liquid.
If there is none you should generally be fine and attempts at disinfection should not be necessary.
If there is you can attempt disinfecting with Calcium Hypochlorite (If this would interact with the 2c-b, somebody chip in), you will need INCREDIBLY small amounts (500g Calcium Hypochlorite can treat nearly 40,000 litres of water, and costs very little).
assuming you used the correct amount of Calcium Hypochlorite there should be absolutely no risk of toxicity to yourself.
usually you would put 7g Calcium Hypochlorite to 8 litres of water, then use ONE PART of that solution per ONE HUNDRED parts of contaminated water then leave it to sit for an hour before consumption.
1.1g per litre
1.1mg per ml
so at this 1:100 ratio, 0.5ml should treat your 50ml solution (about 0.5mg Calcium Hypochlorite)
If you make any Calcium Hypochlorite solution, you will be best off disposing any leftover of it, it doesn't last too long in solution.