A convenient replacement for cyanogen bromide-activated solid phases in immunoradiometric assays.

Periodate oxidation of Sephacryl and Sephadex gels (Pharmacia) and the subsequent coupling of the IgG fraction from antisera has been investigated as a possible, more convenient system to replace the potentially hazardous cyanogen bromide activation of Sepharose which is currently used to produce solid-phase linked antibody for use in sandwich immunoradiometric assays (IRMA). A solid phase based on Sephacryl S300 was found to be a suitable replacement. Under optimum conditions of periodate oxidation and protein concentration during coupling a Sephacryl S300 solid-phase antibody was produced which, in an IRMA for human alphafetoprotein, behaved favourably in terms of high binding capacity and low non-specific binding. Both the final solid-phase preparation and the intermediate oxidised gel were stable for several weeks.