The common practice in determination of calcium and magnesium includes
Ion chromatography with CD
Due to certian practical reason, I am thinking of a HPLC method with UV/VIS detector for the simultaneous determination of magnesium with trace calcium. I went through a brief search from internet and found the following abstracts
Determination of Calcium and magnesium in water samples by HPLC on graphitic staionary phase with mobile phase containing o-cresolphthalein complexone by Pual etc
Simultaneous determination of Na, K, Mg and Ca ions in milk products by indirect photometri HPLC by Jeffrey etc.
If some one has these articles, a pdf copy will be greatly appreciated.
Any other related references or suggestions will also be appreciated.
Edit: asked on forums, answered on forums.