Patent ID: 7029856

Claim:
A heterogeneous immunochemical method for the determination of an analyte in a sample in a liquid medium, comprising: a) incubating the sample in a reaction vessel with a particulate solid-phase on which a first binding partner which specifically binds to the analyte is immobilized and with a second binding partner which specifically binds to the analyte, wherein a fluorescent or chemiluminescent label is conjugated to the second binding partner, and wherein after addition of the solid-phase and the second binding partner the solid-phase is suspended in the liquid medium, whereby the second binding partner is partitioned between the liquid medium and the particulate solid-phase and the solid-phase is subjected to magnetic or gravitational attraction to attract the solid-phase in the liquid medium to an interior surface of the reaction vessel; b) removing the first liquid medium from the solid-phase prior to adding a second liquid medium to the solid-phase; c) resuspending the solid-phase in the second liquid medium; d) adding a reagent A, which causes a separation of the solid-phase and the label by elimination of at least one intermolecular linkage which is essentially composed of hydrogen bonds and ionic, hydrophobic and van der Waals interactions; e) removing the solid-phase by magnetic or gravitational attraction; and f) determining the amount of analyte in the sample, wherein the reagent A contains in aqueous solution one substance selected from the group of reagents consisting of: a chaotropic agent, and a buffer for adjusting the pH to a range of 1.5 to 3; wherein a) through f) are performed in sequential order.