APPLICATION OF MULTILAYER ANALYTICAL FILM TO ELISA OF VANILMANDELIC ACID

The urinary level of vanilmandelic acid (VMA) is one marker for diagno sis of neurblastoma in neonates. A large number of samples are needed for mass screening. In order to make a convenient and sophisticated as say, we examined a method based on dry chemistry by using a monoclonal antibody to VMA. The antibody adsorbed on the surface of the well of a microplate was equilibrated with VMA labeled with glucose oxidase (G OD-VMA). Free VMA in a sample competes with GOD-VMA for the binding si tes of the antibody. An aliquot containing the excess GOD-VMA was spot ted onto a multilayer film consisting of a spreading layer containing glucose and a reaction layer containing peroxidase and a leucodye. Hyd rogen peroxide produced with GOD-VMA in the spreading layer penetrated the reaction layer and produced a blue dye. The amount of dye formed was measured by a reflection photometer. From a standard curve, VMA wa s measurable from 0.1 to 50 mug/ml. The values obtained by the present method were correlated with those by high-performance liquid chromato graphy and enzyme-linked immunosorbent assay. (C) 1994 Academic Press, Inc.