Angiotensin II, RIA
After extraction of the plasma samples, angiotensin II is assayed by a competitive radioimmunoassay. This radioimmunoassay is using a rabbit anti-angiotensin II antiserum and a radio-iodinated angiotensin II tracer.
Bound and free phases are separated by a second antibody bound to solid phase particles, followed by a centrifugation step. The radioactivity in the bound fractions is measured and a typical calibration curve can be generated.