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In this new photometric assay fecal samples are pretreated with detergent and high concentrations of salts. The subsequent kinetic enzyme determination step involves the chromogenic substrate succinyl-Ala-Ala-Pro-Phe-4-nitroanilide. The sample pretreatment assures a nearly complete solubilization of the formerly particle-bound enzyme, thus permitting determination of the enzyme activity in either the suspension or the supernate after centrifugation. Furthermore this pretreatment enhances the enzyme activity and decreases the Km value. Results by this assay correlate well with those by classical titrimetry and the method is easily adapted to automated systems.

An enzymatic method for the calibration of a turbidimetric lipase assay is described, based on measurement of free fatty acids liberated by the action of lipase. The substrate of the turbidimetric assay is a colipase-containing triolein emulsion. For determination of the free fatty acids a commercial test kit including acyl-CoA synthetase, acyl-CoA oxidase, and peroxidase is used. Intra- and interassay imprecision (CV) is about 5% at above-normal lipase activities, about 10% at normal values. Temperature coefficients are 1.24 and 1.45, respectively, for measurements at 30 and 37 degrees C vs 25 degrees C.

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