Further modification of a technique for radioimmunoassay of insulin.

Since our original report we adapted a modification of the immunoassay procedure that increased the sensitivity and reproducibility of the assay. The differences between the present procedure and the previous one are: (a) an initial 20 hour incubation period before the addition of the tracer insulin, and (b) incubation at 37 degrees C instead of 4 degrees C. The adapted method resulted in standard curves of similar slope for bovine, porcine, rhesus monkey, canine and human insulin. The validity of the assay for bovine insulin was established by recovery and dilution experiments.