Alexa Fluor 680 goat anti—rat IgG is labeled with our superior far-red—fluorescent Alexa Fluor 680 dye and is prepared from affinity-purified antibodies that react with IgG heavy chains and all classes of immunoglobulin light chains from rat. To minimize crossreactivity, it has been adsorbed against mouse IgG, mouse serum and human serum prior to conjugation. Fluorescence of this long-wavelength Alexa Fluor dye is not visible to the human eye but is readily detected by most imaging systems.