Measurement of insulin during isolation and purification from animal pancreas. A comparison of radioimmunoassay, radioreceptor assay and in-vivo bioassay.

For the purpose of monitoring the yield of the insulin extraction procedure from animal pancreas three methods of insulin determination were compared, i.e. the mouse convulsion test, a radioreceptor assay (RRA) on rat fat cells and a radioimmunoassay (RIA) which was especially laid out for high insulin concentrations. In samples containing actually insulin in general all three methods provided comparable results. Notable differences were only found in proinsulin-containing material. Because of its simplicity and high reproducibility as well as the good agreement of its results with those obtained with the other assays, the RIA turned out to be the most suitable assay. On the other hand, the RRA should be useful in detecting molecular differences between the investigated insulin-like preparations and standard insulin.