CQ1 is designed to be a superior quencher alternative to DABCYL. Compared to DABCYL, CQ1 have (a). much stronger absorption; (b). much higher quenching efficiency; and (c). versatile reactive forms with desired solubility for labeling oligonucleotides and peptides. This CQ1 product is primarily used for labeling peptides. It is also used for post-labeling thiol-modified oligonucleotides.