[jeffy]

My preferred sanitizer is iodophor.  I was told years ago by a kitchen health inspector that as long as the color in the iodophor/water mix is amber, then it is effective.  When left in an open container that color fades within a couple of days. 
In the last year I have adjusted my packaging regimen to closed transfer into kegs (filled with sanitizer and then pushed out with CO2) before transfer.  I have been reusing the sanitizer from keg to keg to keg and since I cannot see it, I have no idea if it is still amber.
The question is, does the sanitizer lose its effectiveness with age or with oxygen exposure or both?
Maybe next time I’ll take a little sample during transfer.

[hopfenundmalz]

Iodine test strips determine the effectiveness.

https://preclaboratories.com/product/iodine-test-paper/

Some Brewer friends said the inspector asked where their test strips were. They said they laughed, as they mix new solutions everyday. Don't know if they got dinged or not.

[denny]

Jeff, I'll pass your questionm along to the people that make BTF  iodophor.

[Robert]

I make up a new supply every time that I need to use it and discard at the end of the session.  One of the great things about iodophor is that it's cheap enough to do so,  especially if you buy it by the gallon -- which will last a very long time, and AFAIK it does not degrade in concentrated form. 

BTF label says to use a test kit to verify ppm (I'm sure their lawyers made them put that part in,) and immediately thereafter states, "As long as solution is amber color,  there is sufficient iodine present to sanitize.   Make new solution daily or when color fades."

[tommymorris]

OP, can you squirt a little out into a glass with a cobra tap? Then you could check the color.

[lupulus]

Iodine evaporates.

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[Robert]

Iodine evaporates.

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But the amber color is an indicator that positively confirms the presence of iodine.  Try this experiment.   Make up an iodophor solution.  Drop in a Campden tablet or other metabisulfate, which will reduce iodine in the same way it does its fellow halogen, chlorine.   The solution will instantaneously turn colorless.

[lupulus]

You are right. I fail to see the contradiction though.  Iodine evaporates.

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[Robert]

You are right. I fail to see the contradiction though.  Iodine evaporates.

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No contradiction implied.  I'm just thinking that you don't need to know its evaporation rate, or test for ppm,  as long as you have a rough idea of the color corresponding to your desired concentration.   That seems to be the intention of the manufacturers.

The question we're left with is, will the iodine somehow be reduced even in a closed container, by some means other than evaporation?     The instruction to make it up fresh daily isn't qualified by "unless stored tightly covered" or the like.  I'll be interested in hearing what, if anything, Denny learns from National Chemicals.

[lupulus]

You are right. I fail to see the contradiction though.  Iodine evaporates.

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No contradiction implied.  I'm just thinking that you don't need to know its evaporation rate, or test for ppm,  as long as you have a rough idea of the color corresponding to your desired concentration.   That seems to be the intention of the manufacturers.

The question we're left with is, will the iodine somehow be reduced even in a closed container, by some means other than evaporation?     The instruction to make it up fresh daily isn't qualified by "unless stored tightly covered" or the like.  I'll be interested in hearing what, if anything, Denny learns from National Chemicals.

Agreed. My educated guess is that if the container is full (no air) and closed (and room temp) it will stay amber and active (as chlorine does).

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[Robert]

You are right. I fail to see the contradiction though.  Iodine evaporates.

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No contradiction implied.  I'm just thinking that you don't need to know its evaporation rate, or test for ppm,  as long as you have a rough idea of the color corresponding to your desired concentration.   That seems to be the intention of the manufacturers.

The question we're left with is, will the iodine somehow be reduced even in a closed container, by some means other than evaporation?     The instruction to make it up fresh daily isn't qualified by "unless stored tightly covered" or the like.  I'll be interested in hearing what, if anything, Denny learns from National Chemicals.

Agreed. My educated guess is that if the container is full (no air) and closed (and room temp) it will stay amber and active (as chlorine does).

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The only other possibility I can think of is that there might be some potential reaction with minerals in the dilution water.  But that's a less than educated guess.

[denny]

Would anyone mind if I asked someone from BTF iodophor to comment here?

[Robert]

Would anyone mind if I asked someone from BTF iodophor to comment here?

Mind?  Surely I wouldn't.  Exactly what we need is something straight from the people who actually know.

[lupulus]

Would anyone mind if I asked someone from BTF iodophor to comment here?

Thanks Denny. Of course.

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[jeffy]

Would anyone mind if I asked someone from BTF iodophor to comment here?

Thanks Denny. Of course.

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Seems like a good idea.