Wick-chromatography for the Immunoassay of Insulin

Abstract

A simple modification of the chromatographic immuno-assay of insulin is described, using small, dry, vertical chromatographic wicks placed directly in the reaction mixture. The separation of free from antibody-bound radioactivity is accentuated by subsequent additions of small quantities of protein buffer. The advantages of this method consist in (1), fast, easy chromatography of large numbers of samples, (2) better separation of free from bound 131I-insulin than with conventional horizontal chromatography, and (3), the location of maximum activities in the end-pieces of very small strips, facilitating counting. The separation is dependable and uniform, as the migration length of the antibody-bound insulin is equal to the length of the chromatographic strip.