Use of polyoxyethylene ethers to improve the performance of immunoassays employing peroxidase conjugates

In an enzyme-linked immunosorbent assay for an analyte in a patient sample comprising

• (a) incubating the sample in an aqueous assay buffer with an analyte-specific immunoreagent bound to a support, to capture the analyte on the support, and simultaneously or subsequently,
• (b) incubating the captured analyte with peroxidase-labeled analyte-specific immunoreagent to bind labeled immunoreagent to the support,
• (c) separating bound and unbound labeled immunoreagent,
• (d) adding peroxidase substrate solution to the bound, labeled immunoreagent and measuring the resulting enzymatic reaction,
• wherein the patient sample contains blood in sufficient quantity to interfere with immunoassay results, the improvement comprising including in the assay buffer a polyoxyethylene ether detergent in an amount sufficient to improve the signal to noise ratio of the assay.