Abstract: Processes are provided for producing purified, hepatitis B surface antigen particles in mammalian cells which comprise culturing mammalian cells which produce the particles in a culture medium supplemented with a serum free of high molecular weight contaminant proteins and recovering the purified, hepatitis B surface antigen particles.Removal of molecules having a molecular weight greater than about 3.times.10.sup.5 daltons by prefractionation, for example, allows cells to be grown in culture media containing high levels of fetal calf serum, removes high molecular weight contaminant proteins which may be inhibitory to cell growth and simplifies purification of HBsAg since high molecular weight contaminant proteins are the major contaminants removed by purification processes.

Abstract: The present invention provides a method for the separation of anti-metal chelate antibodies from non-specific proteins, including antibodies, by applying a preparation containing the anti-metal chelate antibodies to an oxo acid derivatized solid support and eluting first with an elution buffer containing sufficient salt concentration to elute non-specific proteins but not sufficient to elute the anti-metal chelate antibodies and then increasing the salt concentration of the elution solution so as to elute the anti-metal chelate antibodies. In one embodiment, the oxo acid derivatized solid support is a sulfopropyl resin. Appropriate salts include sodium phosphate, sodium chloride and sodium acetate. The method can be used to separate monoclonal or polyclonal anti-metal chelate antibodies from non-specific proteins as well as to separate bifunctional anti-metal chelate antibodies from monoclonal anti-metal chelate antibodies and other non-specific proteins.

Abstract: A method of separating charged molecules having different numbers of charges thereon includes the step of passing the molecules to be separated through ion-exchange material such as an ion-exchange chromatograpy column in normal manner so that molecules to be separated bind to the ion-exchange material. Displacer molecules are then passed through the ion-exchange column to selectively release certain of the molecules to be separated from the ion-exchange material, while others of the molecules to be separated remain bound to the material.