EDTA is a kind of acid which has a strong complex capacity with divalent cations. However, its complex constants with mono-cations are very weak. In my opinion, either K2-EDTA or Na2-EDTA would not have effect on its chelating function.

Wendong Wang

EDTA is Ethylene Diamine Tetra Acetic acid. EDTA is a tetrabasic acid. It is essentially insoluble in water.The solubility increases as you add NaOH and convert the acid groups to their salts.The disodium salt is soluble in water at room temperature up to a concentration of 0.26 mol/L.The pH of the solution is in the range of 4 to 6.At pH 8.5 a 0.5 mol/L solution at 4 °C is stable for months. The solution is rather viscous and has a pH between 10 and 11.You can use the tetrasodium salt at higher concentrations.The drawback is that you must also work at a higher pH. If pH is not a concern, you should be able to use either salt.A pH of 11 may cause other, unwanted, reactions to occur in your system.You should then switch to the disodium salt and its lower pH.

Thanks for answering Prof. Wendong Wang and Dr. Arkan Radi.

So, do you have suggestion what kind of EDTA that prefer to chelating agent (Metal ions chelation)?

K2-EDTA is preferred because it dissolves better in water regardless of anticoagulant effects? Am I understanding right?

The important thing to consider is the buffersystem you create with the salts. If you have the chance and a pH sensor take blood in both systems. Then open the tube to remove 50ul for pH mesurment. Then do the same again after 30 minutes at >12oC (EDTA blood should be stored above the membrane transition temperature(usually 12 to 14oC)