Ca n Mg free PBS - (Jul/01/2013 )

Can any one tell me how to prepare Ca++ and Mg++ free PBS for cell isolation

Dulbecco’s phosphate-buffered saline (Dulbecco’s PBS)
2.7 mM KCl
1.5 mM KH₂PO₄
136.9 mM NaCl
8.9 mM Na₂HPO₄•7H₂O

Thanks bob1