I got some iodine to do the starch conversion test during my next brew, but I'm not sure it's the right stuff. It's Povidone-Iodine Solution. Will that work?
Easiest way to tell: Try it on a known starch. Mix a tablespoon of water with a sprinkle of corn starch, apply a drop of iodine and see if it turns purple.
Should work fine, found a spec that lists that as 1% available iodine. You can dilute that further with rubbing alcohol (isopropyl alcohol) if the iodine color makes reading the starch test results difficult.
I use 1 part of idophor (1.6% iodine) to 5 parts volume of isopropyl alcohol on either use white sidewalk chalk or the edge of drywall. Apply the wort to the chalk first and the iodine solution second.