Extraction of immunoglobulin-G from colostral whey by reverse micelles

Separation of immunoglobulin G (IgG) from the other colostral whey proteins was carried out by reversed micellar extraction. The colostral whey was diluted to 5 times its original volume with 50 mM phosphate buffer at pH 6.35 containing 100 mM of sodium chloride. The aqueous solution was then mixed with an equal volume of isooctane containing 50 mM bis-(2-ethylhexyl) sodium sulfosuccinate (AOT), and shaken at 200 rpm and 25degreesC for 10 min. After extraction, the mixture was separated to the aqueous phase and the reversed micellar phase by centrifugation. This procedure extracted most of the non-IgG proteins to the reversed micellar phase and recovered more than 90% of the IgG in the aqueous phase. The IgG in the aqueous phase had a purity of 90%, and still possessed immunological activity. AOT was not detectable in the aqueous phase.