TQ3WS is designed to be a superior quencher to TAMRA, TF3 and Cy3. TQ3WS has (a). much stronger absorption; (b). much higher quenching efficiency; (c). good water solubility; and (d). versatile reactive forms with desired solubility for labeling oligonucleotides and peptides. Like TQ3, this TQ3WS product is used for post-labeling of thiol-modified oligonucleotides and and cysteine-containing peptides. TQ3WS has much higher water solubility than TQ3.