Spoiler alert….they won’t read identical and have even varied drastically when others have done this exact thing.
Which ICP analyses?
For iodine, I have found the test procedure developed by @thatmanMIKEson , @taricha and @Dan P to be very helpful.
You should check it out if you want an iodine test to use between ICP runs.
AN ACCURATE AND PRECISE METHOD FOR MEASURING IODINE
ABOUT THE ARTICLE: The article describes an accurate and precise method and it's development, for measuring the level of Iodine in a saltwater aquarium. It is a follow-up to an article written in 2021. The current article describes an improved method but using the same basic ideas as the 2021...www.reef2reef.com
I saw that a while back. Great data in there.