Abstract: A double antibody radioimmunoassay method for determining antigens in a sample wherein polyethylene glycol is provided in a reaction medium to accelerate an immunoprecipitation reaction between water-soluble first antibodies bound to antigen and water-soluble second antibodies which are not specific to said antigens but which are specific to said first antibodies. A double antibody, multi-component radioimmunoassay test kit is also provided. The kit contains radiolabeled antigen reagent, first water-soluble antibody reagent and second water-soluble antibody reagent, as well as a polyethylene glycol reagent, which may optionally be combined with the second antibody reagent, in an amount sufficient to accelerate an immunoprecipitation reaction, between said first and second reagents.

Abstract: A method and reagent for counteracting lipemic interference in an assay of a lipid-containing sample, e.g. blood. The method includes the steps of: (a) mixing with the sample prior to or during said assay a high surface area, finely-divided adsorbent having an affinity for lipids, and a nonionic, water-soluble polymer, and (b) precipitating adsorbed lipids in said sample. The reagent includes a high surface area finely-divided adsorbent, and a nonionic, water-soluble polymer having a molecular weight of from about 1,000 to 100,000.