Removal of organic solvent from antibiotics with supercritical carbon dioxide

Organic solvents were rapidly extracted from penicillin G potassium and streptomycin sulfate with supercritical carbon dioxide (SC-CO₂) at 200 atm and 35°C without loss of antibiotic activities. The amounts of organic solvents remaining in the antibiotics depended upon pressure and temperature for a given extraction time. A semilogarithmic plot of remaining amounts of organic solvents against extraction time gave a straight line in the early extraction stage, allowing prediction of the extraction time required for decreasing amounts of organic solvent. The addition of water as an entrainer to SC-CO₂ resulted in a significant increase in extraction rates.