BREA, Calif., Sept. 23, 2010 — Beckman Coulter Inc. has introduced Krome Orange, a violet-excited organic dye that expands the range of available choices and dye sensitivity limits for violet lasers. Common gating markers can be easily transferred to this fluorochrome, freeing other channels for use with more esoteric markers and enabling more versatile 10-color flow cytometry applications. Krome Orange has excitation and emission maxima of 398 and 528 nm, respectively, and provides a brighter signal than Pacific Orange conjugates with equivalent spectral overlaps into adjacent channels. It is at least as bright as V500 and can provide more than twice the population separation obtained with Pacific Orange dye conjugates, with little compensation compared to Pacific Blue dye, according to the company. Krome Orange conjugates show optimal performance with violet laser excitation and a 550/40 bandpass filter (the standard FL10 channel on flow cytometry systems), while no excitation is detected using a 488-nm laser. The initial release includes conjugates to human CD45 and CD4, with the range of human and mouse targets to expand going forward. The dye enables scientists to increase sensitivity for low fluorescence signals and to expand their flexibility for multicolor flow cytometry experiments.