J.R. S. answered 11/25/19
Ph.D. University Professor with 10+ years Tutoring Experience
Well, we'll need a little more information that what you've provided. Essentially, to find the concentration of an ion (or anything else for that matter), you will need the volume of solution along with the moles or mass of the ion. Then for a molar concentration, it will be moles/liters; for mass concentration you can express it as grams/ml.
If you have a specific example, why not post it?