I've tested for Strontium before, and it was a very involved test (Salifert). Fortunately, the number was perfect.
Iodine can be tested for, but as a general rule iodine is used up very quickly in a tank. Many people don't dose it, while others just add a drop or two each week. Don't overdose it thinking it wasn't enough. I added a drop of Lugol's Solution in my 29g years ago, and thought "that was nothing!" and dropped in a second drop. Suddenly my clownfish were gasping and jerking around, and I stood there helplessly thinking I'd just murdered my fish. Fortunately, they were okay 10 minutes later. I never did that again. Iodine is added to some fishfoods available at the LFS, and is part of the salt mix. It even is included in B-Ionic, if you dose that.
I don't know of a test for the third element you listed.
