By using trypsin as the model protein and AOT as the model surfactant, the effect of a variety of solvents on protein transfer and activity recovery during the liquid-liquid reversed micellar extraction was investigated. It was found that several solvents, including isooctane, octane, heptane, and kerosene, had a similar effect on the recovery of trypsin activity after a full cycle of forward and backward extraction, and could all be used as the solvents for AOT-reversed micelles in trypsin extraction. Two other solvents (hexane and cyclohexane), however, were not so efficient. (c) 1995 John Wiley & Sons, Inc.