Field of Science


I am looking around for a specific indicator for ferric ions that's very specific for ferric over ferrous. It should be water soluble and stable at room temperature and neutral or basic pH. In addition, it should be very sensitive and should be able to detect slight increases in ferric concentration by a bright colour change. And of course, the colour change should be easily detectable by a spectrophotometer, or more preferably, by the human eye.

Help will be much appreciated!


  1. Quite ignorant, but what about potassium ferrocyanide? Can one also use the heme group of hemoglobin?

    Anyway, good luck :)

  2. I don't have any particular recommendations...but with all the fluorescent/colorimetric sensors out there, it can't be too hard to find something, can it?

  3. That's what I am assuming. Thanks, both of you. I was just feeling a little lazy ;)

  4. I had read something about rubeanic acid being used to detect ferric ions. Potassium cyanoferrate too does give a particular colour with ferric(turns blue i believe!)

  5. What about thiocyanate? It forms a blood-red color with ferric ions, but is colorless with ferrous ions, IIRC. It's what I used to use to detect iron.

  6. Thanks, that's a good idea. Is that water soluble though?


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