A little bit of info I found about Iodine containers ( I love Google!)<br><br>Make only as much iodophor sanitizing solution as you need for each use. Iodine is volatile and will outgas from the solution with time, losing its sanitizing ability. You may have noticed that an iodine solution left in an open glass jar will lose its brown color. If you do have leftover solution, store it in a tightly sealed glass jar or a PET plastic soda bottle. Solution stored this way is stable for about a week. Do not store the solution in other types of plastics because they will either absorb the iodine fairly quickly or allow it to volatize because of their gas permeability, again causing a loss of sanitizing ability.<br><br>http://realbeer.com/jjpalmer/cleaning.html<br><br>Because handwashing in all settings is so poorly practiced, gloves are ordered in patient<br>care and food preparation areas by regulators. As a comment to this rule change, a study<br>was submitted to the US FDA concerning a polypropylene wiper coated with PVP-I to<br>deliver 750-1250 ppm of free iodine.8 Test subjects were repeatedly contaminated with<br>cultures of S. marcesans over a two hour period, and instructed to clean-up using only a<br>water rinse, and 15 second wipe with the wiper. Their hands were swabbed and culture<br>test results recorded.<br><br>http://www.biolargo.com/hunter-killer.pdf <br><br><br>The references follow the excerpts.<br><br>Seems from the first excerpt that PET is a better storage material than "other plastics"<br><br>Seems from the second post that they are using polypropylene as an applicator wipe soaked in sterilizing concentrations of free iodine solution. Leads me to believe that polypropylene will not degrade in this application. Still may be too gas-permeable as mentioned in the first excerpt. <br><br>Still looking for a definitive result. Does anyone know of a chemical test for presence of iodine that I could run on the outside of my test container?<br><br>Brad