A semi-automated radioimmunoassay technique employing a nine-channel pipetting and sample handling.

A semi-automated RIA-technique has been developed which employs simultaneous pipetting of nine aliquots of reagents with nine-channel pipettes and the processing of RIA samples in nine-tube units. This processing includes evaporation, centrifugation, and decantation of tubes at the end of separation step of the RIA. The nine-channel pipetting reduced the time necessary for pipetting to about one third as compared to the corresponding one channel pipetting, and made the pipetting less tiresome. The precision of pipetting was also improved. This nine-channel RIA-technique was applied to radioimmunoassays of plasma 17-beta-oestradiol and progesterone, in which [125I]iodohistamine-conjugated steroid-tracers were used.