To 400ml Milli-Q water add:

93.05g Disodium EDTA (Sigma #ED2SS)

-Adjust pH to 8.0 with 10N NaOH or NaOH Pellets

(approx. 10g NaOH pellets needed. Add slowly because it generates heat!)

EDTA will not go into solution until it is pH 8.0

-Bring volume to 500ml with Milli-Q water

-Sterilize by autoclaving wet cycle if needed