Polyethylene glycol Sigma, MW10000
NaCl tissue culture grade (?)
EDTA tissue culture grade precipitate (NaCl)
H2O deionized pyrogen free
0.1N NaOH pyrogen free

Add 100g PEG and 6g NaCl to 250ml H2O in 500ml bottle. Mix. Autoclave at 15lb for 20 minutes. Allow to cool. Adjust pH with NaOH to pH 7.2 under sterile conditions.