Polysciences offers europium chelate microspheres in a sampler pack (1mL of 0.10μm, 0.20μm, 0.30μm) to address the needs of individual assays, including immunochromatographic and microwell-based formats. Our europium products offer extremely bright fluorescence and exceptional stability, in addition to well-functionalized carboxylated surfaces for the covalent attachment of ligand.