99.5% acetic acid would be such a painful injection. Believe me, you don't want to do that. Even .6% has a sting. In the past, I had purchased medical grade AA, but it has been harder and harder to come by. Since then, I have taken to making it on my own. It works just fine. Heres what you'll need. Distilled white vinegar and distilled water found at your local grocery store. You can also use sterile water for injection instead of distilled water .22mm syringe filter, a 3cc syringe, 10cc sterile vial. 

Using your 100 syringe, draw up 7.5cc of distilled water (or sterile water), add 1cc distilled vinegar. Then push this solution through your filter and a clean needle, into your sterile vial. Be sure to clean the surface of your vial before hand. Thats it. It has work for me, with no issues, for the last year.