Portelite™ Rapid Fluorimetric Biotin Quantitation Kit is specifically optimized to quantify biotin and biotin conjugates with a portal fluorometer such as CytoCite™ and Qubit™ Fluorometer. The kit uses Biotinylite™ Green, a fluorogenic biotin sensor. Biotinylite™ Green is almost non-fluorescent and give strong green fluorescence upon interaction with a biotin or biotin conjugate. The concentration of biotin is proportional to the fluorescence intensity of Biotinylite™ Green. The amount of biotin is determined by comparing a sample’s fluorescence to the predetermined biotin standard curve. This fluorescence-based assay is much more sensitive than the commonly used colorimetric HABA assay. Biotin is a relatively small molecule that is routinely conjugated to antibodies and proteins with minimal interference of their biological activity. The avidin/streptavidin-biotin interaction is the strongest known binding pair between a protein and its ligand. The biotin-avidin interaction has been extensively explored for a variety of biological applications.