The Zen™ Myeloperoxidase (MPO) ELISA Kit provides a comprehensive set of components for accurate and sensitive quantitation of MPO in a variety of biological samples, including human serum. The assay is based on Amplex® UltraRed reagent, a fluorogenic substrate for horseradish peroxidase (HRP) that reacts with H₂O₂ in a 1:1 stoichiometric ratio to produce the Amplex® UltraRed product, a brightly fluorescent and strongly absorbing product (excitation/emission maxima ~568/581 nm). With a high extinction coefficient, good quantum efficiency, and resistance to autooxidation, the fluorescence-based Amplex® reagent delivers better sensitivity and a broader assay range than colorimetric reagents. Each kit contains sufficient reagents for ~200 assays in a microplate format, using a 100 µL per well reaction volume. The microplate-based formulation provides speed and convenience yet is highly sensitive, and it can be used to detect MPO over a broad dynamic range (0.2 to 100 ng/mL) at room temperature.