A simple and rapid technic for radioimmunoassay and calculation of plasma steroid concentrations.

A simple RIA technic for plasma steroids is described: Extraction residues or reference standards are dissolved in 20 microliter ethyl alcohol, or 20 microliter of alcoholic plasma extracts are given directly into RIA tubes; 500 microliter tracer solution, containing a known tracer mass, and, after mixing, 500 microliter antiserum solution or buffer solution are added, followed by 20 min incubation at room temperature and 20 min standing in an ice bath. Free from bound activity is separated by charcoal coated florisil or silicagel. Plasma steroid levels are calculated by a simple equation. An immunologic equivalent to the tracer mass present in the reaction mixture serves as reference value. Drawing of standard curves is not necessary for every assay. The linear transformation used here allows the number of reference standards to be reduced. So also single samples can be analyzed with relatively low effort.