The different about disinfectant to antiseptic?
A disinfectant is used to destroy microorganisms off of any surface.
An antiseptic is used to destroy microorganisms off of the skin.
So you have to take a little more care in choosing an anti-septic then a disinfectant.
Magic acid would do well as a disinfectant but would be an unwise chose for an anti-septic as it would probably kill the patient as well as any septic organisms.
PLEASE PLEASE PLEASE everyone except trained professionals stay away from magic acid.