Biotin phosphoramidite contains a DMT group to allow quantification of coupling. It is soluble in acetonitrile, providing a valuable tool to add the biotin tag to a 3’ or 5’ location of an oligo sequence. Biotin phosphoramidite contains a 15-atom spacer arm minimizing the potential hindrance of biotin binding. It is complimentary to the commonly used biotin phosphoramidite that contains no DMT group and can only be added at the 5'-terminus, thus terminating synthesis. The DMT group on biotin phosphoramidite can be used in RP cartridge and HPLC purification techniques. AAT Bioquest also offer biotin-dT phosphoramidite and biotin-dT CPG.