A Photometric Method for Serum Lipase with. 2-(2-Thiazolylazo)-p-cresol

Abstract

The method described allows a relatively rapid and sensitive assay of lipase activity in serum by the use of olive oil as a substrate. We have modified the photometric, copper soap method for determining fatty acids described by Maehata and Naka (Jap. J. Clin. Chem., 1, 447 (1972)). The free fatty acids are separated in the form of their copper salts by chloroform-heptane extraction and organic layer is obtained as a supernatant by centrifugation. Copper is determined by colorimetry with 2-(2-thiazolylazo)-p-cresol. Centrifugal procedure is carried out lust once differing from other colorimetric method.
The site of the action of lipase is the interface between the oil drops and the aqueousphase, so that the degree of emulsification plays an important part in establishing the active substrate concentration. Therefore, Preparation of substrate emulsion, such as pH, kind of buffer, olive oil concentration, arabic gum concentration, and mixing condition, has to be made most carefully.
The precision of the method was satisfactory and the relationship between this assay and Cherry-Crandall 3-hour method was close. The method is suitable for estimating lipase activity in a Clinical laboratory