QXL™ 490 dyes are the optimized quenchers for EDANS, AMCA and most coumarin fluorophores. Their absorption spectra perfectly overlap with the fluorescence spectra of EDANS and AMCA. This characteristic makes QXL™ 490 dyes excellent quenchers for EDANS, AMCA and coumarin fluorophores. QXL™ 490 C2 amine readily reacts with carbonyl-containing compounds.