ENZYMATIC FLOW-INJECTION ANALYSIS IN NONAQUEOUS MEDIA

A novel enzymatic flow injection approach is proposed, involving the use of noncovalently immobilized enzyme reactors operating in nonaqueous media. The feasibility of this approach was tested and successfully demonstrated using as a model system a coimmobilized cholesterol oxidase-peroxidase reactor for the determination of cholesterol in toluene. The response was linear up to 1.8 X 10(-4) M cholesterol, with a detection limit of 10(-6) M. The throughput was 60 samples/h. The reactor was stable for more than 4 months with a half-life of 81 days. The strategy developed combines the remarkable benefits offered by enzymology in organic solvents and the advantages inherent in flow injection methods. Among them, the biocatalyst can be immobilized in a rapid, complete and irreversible manner by simple adsorption to the solid support; poorly water soluble compounds can be readily dissolved in the mobile phase and directly analyzed; and most importantly, the enzymatic reactor exhibits an enhanced stability in the water-restricted environment.