Method to produce an immunoglobulin preparation with improved yield

A method for preparing an enriched IgG composition from plasma, the method comprising the steps of:

• (a) precipitating a cryo-poor plasma fraction, in a first precipitation step, with from about 6% to about 10% alcohol at a pH of from about 7.0 to about 7.5 to obtain a first precipitate and a first supernatant;
• (b) precipitating IgG from the first supernatant, in a second precipitation step, with from about 23% to about 27% alcohol at a pH of from about 6.7 to about 7.1 at a temperature of from −7° C. to −9° C. to form a second precipitate;
• (c) suspending the second precipitate to form a suspension;
• (d) precipitating IgG from the suspension formed in step (c), in a third precipitation step, with from 22% to 28% alcohol at a pH of from 6.7 to 7.3 to form a third precipitate;
• (e) re-suspending the third precipitate to form a suspension;
• and
• (f) separating the soluble fraction from the suspension formed in step (e), thereby forming an enriched IgG composition.