The B-Bridge ANP Immunoassay kit is designed to quantitatively measure ANP present in plasma, urine and tissue culture media samples. An ANP standard is provided to generate a standard curve. Standards or diluted samples are pipetted into a clear coated microtiter plate. An ANP-peroxidase conjugate is added to the standards and samples in the wells. The binding reaction is initiated by the addition of an antibody to ANP to each well. After an hour incubation the plate is washed and substrate is added. The substrate reacts with the bound ANP-peroxidase conjugate. After a short incubation, the reaction is stopped and the intensity of the generated color is detected in a microtiter plate reader at 450nm.