Goat anti-human IgM (mu chain) is labeled with CF®,640R dye. CF®, dyes are Biotium's line of next-generation fluorescent dyes with advantages in brightness, photostability, and conjugate specificity compared to other fluorescent dyes. Far-red fluorescent CF®,640R dye has excitation/emission at 642/662 nm. It is prepared from antibodies purified by human IgM-affinity chromatography. The antibodies react specifically with IgM heavy chains (mu chains) and not with immunoglobulin light chains. To minimize crossreactivity, it has been adsorbed against human IgG prior to conjugation.