The QUANTOMâ„¢ Viable Cell Staining Kit is used to label live bacterial cells for counting with the QUANTOM Txâ„¢ Microbial Cell Counter. The QUANTOMâ„¢ Viable Cell Staining Dye is a less toxic Calcein AM derivative that has better cellular retention and efficiently labels difficult-to-stain cells such as live bacterial cells. In live cells, intracellular esterases cleave the acetoxymethyl (AM) group, producing the membrane-impermeable fluorescent Calcein. The optimal excitation/emission wavelength is 496/520 nm. QUANTOMâ„¢ Viable Cell Dilution Buffer enhances the fluorescence signal of cells stained with QUANTOMâ„¢ Viable Cell Staining Dye and is used to wash or dilute bacterial cells prior to staining. QUANTOMâ„¢ Cell Loading Buffer I is a gradient medium used for the even distribution and sedimentation of bacterial cells in QUANTOMâ„¢ M50 Cell Counting Slides.