Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Determination of Ca/Mg in orthophosphate-rich solutions

  1. Feb 6, 2017 #1
    I want to measure the Ca and Mg concentration in a solution that contains up to 250 mg/L of PO43-. Apparently, orthophosphates interfere with both flame photometric methods and complexometric methods with EDTA (or so I've read). Is there a standard method for measuring Ca and Mg in this type of solution?

    I am more preferring complexometric methods at the moment because our atomic absorption spectrophotometer is not functioning well. Thank you!
     
  2. jcsd
  3. Feb 6, 2017 #2

    Borek

    User Avatar

    Staff: Mentor

    Complexometry is a gold standard here.

    Problem with orthophosphates is that for EDTA titration you need a high pH, and in high pH and in the presence of orthophosphates you can expect precipitation of weakly soluble magnesium and calcium salts. I am not aware of any standard method of dealing with such situations (doesn't mean there is no one, its been ages since the last time I had to deal with these titrations). I would check if there is no other chelating agent that works nicely in lower pH.
     
  4. Feb 6, 2017 #3
    I found one paper that proposed an alternative titration method that eliminates orthophosphate interference but it was published in 1961. I was wondering though that there was a standard method that I have not yet read about.
     

    Attached Files:

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Determination of Ca/Mg in orthophosphate-rich solutions
Loading...