EDTA Complex HCl Digestion

[gmartinetti01]

I want to break down multiple EDTA complexes for atomic absorption spectroscopy (FAAS). Does anybody know how much HCl should be added relative to the (liquid) EDTA complexed samples aliquot? I want to make sure I fully protonate the EDTA to leave all metals in their ionic form for analysis, but I'm not sure how much acid this would require for each complex (Zn, Mn, Mg, Ca, Cu, Fe). Would the stoichiometric ratio just be 4 mol HCl to 1 mol EDTA (+ a little extra for safe keeping) or should I be putting in more/ less HCl?

 

Any help is appreciated.

[chenbeier]

EDTA-metal is a 1:1 complex. That mean for the alkaline-earth metals and most transitionmetals you need per mol metal two mol HCl. So you have to know the concentration of the EDTA and also roughly the metal concentration obtained by the titration.

Edited December 6, 2018 by chenbeier