calcium dissolution

[Andrea Hilton]

I want to perform a dissolution profile for calcium with vitamin D tablets as per USP, but I need to quantify the calcium amount by titration with EDTA. Each tablet has 500 mg of calcium and the volume of dissolution media is 900 mL. Can anyone suggest me a titrimetric method for determination of calcium when I have from 10% to 120% of the labelled amount of calcium dissolved in the dissolution media?

Thanx,

Andrea Hilton

[Andrea Hilton]

Or a HPLC method with UV detection...

Thanx,

Andrea

[Bill Tindall]

I'm confused. You say you are going to titrate with EDTA. What more information do you need? Filter off undissolved calcium, adjust pH to 10ish with NH3/NH4+, Erichrom Balck T indicatior and away you go. May need a touch of CN- if transition metals are present. Any analytical text will have the details.