QXL™ 570 dyes are optimized quenchers for rhodamines (such as TAMRA, sulforhodamine B, ROX) and Cy3 fluorophores. Their absorption spectra perfectly overlap with the fluorescence spectra of TAMRA, sulforhodamine B, ROX and Cy3. This characteristic makes QXL™ 570 dyes excellent quenchers for rhodamines (such as TAMRA, sulforhodamine B, ROX) and Cy3 fluorophores. QXL™ 570 acid can be coupled to amino groups via EDC-mediated reactions.