A Radioimmunological Assay Method for Insulin Using Insulin-125I and Gel Filtration

Abstract
A radioimmunological assay for insulin is described using insulin-I125 as a tracer and gel filtration on Sephadex G75 to effect the separation of bound from free insulin. The relatively long half-life (60 days) and the absence of [beta] radiation by this isotope decreases the radiation hazard encountered during iodination procedures. As little as 0.25 [mu]U of insulin can be reliably measured by a single tracer for 6 months.