I do think that some of the Vit C is ascorbate, which is a form of ascorbic acid. Even the other types of Vit C are probably ascorbic acid at their core, but I am not really sure.
No Vit C is citric acid , although it may have citric acid added as a flavor (ie - the Emergen-C products come in a citrus flavor).
I did not have any luck finding citric acid locally, but I was able to order it from my pharmacist, USP grade, and it was in the next day. Supposedly some health food stores do carry it, and some supermarkets carry it as "Sour Salt" in the Kosher section.