Patent ID: 8076448

Claim:
A method for obtaining a purified biodegradable PLG copolymer polyester, the method comprising extracting a poly(DL-lactide-glycolide) (PLG) polyester with a supercritical fluid comprising carbon dioxide to obtain the purified biodegradable PLG copolymer polyester, wherein the purified biodegradable PLG copolymer polyester dissolves in the supercritical fluid and is recovered by evaporation of the supercritical fluid, wherein the poly(DL-lactide-glycolide) (PLG) polyester is fractionated by a series of successive extractions with the supercritical fluid, wherein each successive extraction is carried out at a higher pressure; wherein a first extraction pressure is at least about 1,000 psi and the successive extractions at higher pressures are carried out at pressures increasing up to about 12,000 psi; and wherein the extractions are carried out at a temperature of at least about 50° C., optionally increasing to about 100° C. during the successive extractions.