Purchasing Citric Acid

Hi,

I will be needing to make up a batch of MMS1 from flakes soon. Shopping around for Citric Acid powder and found some with the Ball Canning Jars. It's used for canning fruits and veggies. My question is that it also has something in it to prevent caking of the powder. I am not sure what it is called but I am wondering if I am going to be able to find just pure CA. Is the CA that people are using to make MMS1 the same thing as what I am seeing in stores that has that anti-caking addition?

Terry, I get mine at MountainRoseHerbs - online - I don't think it has caking agents. You can also find it on ebay.