Abstract: For the immunological determination of PSA-ACT complexes in a sample to be examined in which the sample is contacted with at least one antibody that specifically binds the complexes or their components or with specifically binding fragments thereof in which the antibody is bound to a solid phase or can be bound to a solid phase, a test liquid is used according to the invention which contains 0.5 to 2.5 mol/l of an alkali chloride at least during contact between the sample and the solid phase. A buffer system according to the invention for a PSA-ACT test contains 0.5 to 2.5 mol/l, preferably 1.5 to 2.0 mol/l alkali chloride in addition to other common buffer substances.

Abstract: A carrier fleece is prepared for use as reagent carrier from which reagents can be dissolved in as assay such as immunological analysis. The carrier fleece contains from 5 to 60% by weight of cellulose-containing fibers, from 40 to 95% by weight of polyester or polyamide polymer fibers or a combination thereof and from 5 to 30% by weight of the fibers of an organic binding agent which has a hydroxyl or an ester group or a combination thereof. In an immunological analysis, the carrier fleece is impregnated with an immunologically active agent such as a beta-galactosidase conjugate and then introduced into a solution of a sample containing an immunologically active substance to be analyzed. The immunologically active agent is eluted into the sample solution and the presence of the immunologically active substance in the sample is determined.

Abstract: The invention teaches a method for improving the ability to determine a polyvalent substance via use of an immunoaggregate during the assay. The immunoaggregate eliminates substances which can lead to incorrect results otherwise.