To serum, add 2 volumes of 27% Sodium Sulfate

Precipitate 30 minutes at room temperature

Decant into ss-34 rotor tubes, spin 8000rpm for 30 minutes
(Save supernatant just in case)

Resuspend pellet in about 1 original serum volume of 18% Sodium Sulfate

Spin again at 8000rpm

Dissolve in 1 original serum volume of PBS

Dialyze against PBS at room temperature or 4°C for 4 hours.