The concentration of the solution tested was 80 micrograms/ml creatine, which equates to 5 grams of creatine in 2.2 fluid ounces at a degredation rate of ~3% per day (unless my stats are off).
Just copied and pasted what I posted a while back. Obviously the degredation rate varies according to the method used to analyze it but it seems to be less, at least according to that article, than most folks think, including myself. 'Course, I could have calculated that percentage incorrectly since I'm not stellar at statistics