Abstract
A new method was developed using flow injection analysis (FIA) with amperometric detection for determining the activity of esterases, such as lipase and cholinesterase. Such esterases catalyze hydrolysis reactions of the substrate esters to release constituent acids. The released acids were determined based on current height of the reduction prepeak of quinone. Olive oil, as a substrate, produces higher fatty acids through lipase enzyme reaction. Benzoylcholine or acetylcholine, as a substrate, produces benzoic acid or acetic acid through cholinesterase enzyme reactions. Samples containing the enzymes were incubated with a substrate at 37°C, and test solutions were prepared. The released acids in the test solutions were determined by FIA. Enzyme activity in the samples was subsequently calculated. The relative standard deviation of activity values in human serum were less than 3% (n=5) in all cases. Good correlation was observed for the present and conventional methods in lipase and cholinesterase activity determinations, respectively.
