Vitamin C and Iron

I know it is suggested that you take Vitamin C with your Iron but how much vitamin?  I see pills that are 500 or 1000 etc.   I am pre-op at the moment and cannot use the chewable Vitamin C.  Anyone have an idea?

I take 500 mg with each iron pill (Ferrous Sulfate).  You might be able to get it in liquid, but not sure.

Cathy