A sensitive kinetic assay of serum albumin based on its enzyme-like hydrolytic activity, using a new chromogenic and fluorogenic substrate.

A new albumin assay, based on the unusual enzyme-like activity of the protein that promotes hydrolysis of ester bonds in fatty acid arylesters was designed for clinical routine use. The substrate introduced shows improved analytical wavelengths and is suitable for both photometric and fluorimetric assay. Experiments have been performed with a conventional photometer, a fluorimeter and a Cobas Fara autoanalyzer. Detection limits are as low as 10 micrograms/ml photometrically and 20 ng/ml fluorimetrically. The method provides a sensitive quantitative determination of even minute amounts of albumin in liquid solution, and a simple semiquantitative test may be performed by fixing the dye on a test strip which then is immersed into a sample solution and observing the development of yellow color intensity.