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Reducing the Use of Organic Solvents

By Linda McGraw
April 5, 2001

Agricultural Research Service (ARS) scientists in Peoria, Ill., are coupling two environmentally friendly techniques to reduce or eliminate the use of toxic organic solvents in the processing of agricultural commodities. The U.S. Environmental Protection Agency has called for a reduction in the amount of toxic solvents released into the environment, which has impacted industrial manufacturers.

Solutions called ionic liquids, salt-like fluids at room temperature, are safer to use than organic solvents like hexane in research laboratories, according to ARS biochemist Joseph A. Laszlo at the National Center for Agricultural Utilization Research in Peoria. In the past, researchers had to use solvents to get enzymes to act as a catalyst for chemical reactions. Now, ionic liquids can be used in place of solvents.

Laszlo and ARS chemist David L. Compton made ionic liquids in their laboratory. They are the first researchers to perform enzymatic reactions in ionic liquids in combination with supercritical carbon dioxide (CO2). They tested the liquids as a solvent for the enzyme chymotrypsin with a commonly used laboratory substrate. This enzyme may catalyze reactions needed to manufacture important chemical ingredients in drugs and skin care products.

Laszlo says that combining ionic liquids and supercritical CO2 results in a superior processing method, which is better than either one alone. In the technique, CO2 is heated and compressed to the point that it becomes both liquid and gas, which is the supercritical state.

Laszlo reported these findings at the 221st annual meeting of the American Chemical Society meeting in San Diego, April 1-5, where he participated in a 5-day symposium on the development of ionic liquids.

ARS is the chief scientific research agency for the U.S. Department of Agriculture.

Scientific contact: Joseph A. Laszlo, ARS National Center for Agricultural Utilization Research, Peoria, Ill., phone (309) 681-6322, fax (309) 681-6685,