There are several ways of labeling an oligonucleotide with fluorescein. The choice of label is diversified further, depending on the spectral requirements. 5’-fluorescein-CE phosphoramidite, derived from the single isomer 6-FAM, 6-HEX, 6-TET and 6-JOE, can all be used to efficiently label an oligonucleotide at the 5’-end. Labeling the 3’-end of an oligo with fluorescein can be achieved using 3’-Fluorescein CPGs. Standard cleavage and deprotection with ammonium hydroxide liberates the fluorescein-labeled oligo when using any of these supports. Although 6-FAM, 6-HEX and 6-TET phosphoramidites have been effectively used for labeling oligos, there is no 6-JOE phosphoramidite available for preparing JOE-labeled oligos. AAT Bioquest offers Helix Fluor JOE Phosphoramidite to facilitate the labeling of oligos with JOE. Helix Fluor JOE Phosphoramidite can be conveniently used to prepare the oligos that have essentially identical spectral and biological properties to the ones that are derived from 6-JOE, SE.