Hi Zhuzhen,

I would go with EGTA, couple mM you are pretty safe. Also, if you don't want to have to use a chelator, you can simply prepare your medium without calcium.

Hope this helps, Norbert

Hi Zhuzhen,

alternatively, you can get culture medium without calcium from usual suppliers.

All the best

Thierry

Thanks for all your help. Since the medium I need that should be without calcium, without glucose, without HEPES, without HCO3-, without phenol red, I can not find one that without all of these reagents. Sigma D5030 medium is much closer, but they contained about 1.8mM Calcium. I will try EGTA chelator. Thanks again for all of your help:-)

You can add a stoichiometric amount  of EDTA to chelate any calcium ions but you need a basic medium

do not hesitate to use a software like Bad4 to calculate the free concentrations of the other ions in presence of EDTA, EGTA or BAPTA :)