Why is purification not recommended for randomized oligos?
Additional purification for oligonucleotides incorporating randomized bases can result in a bias in the degeneracy of the randomized bases. When we purify by either PAGE or HPLC, only a fraction of the full length migrating oligonucleotides are harvested, which has the potential to introduce a strong bias away from an equal molar representation of each species. To avoid this issue, IDT recommends standard desalt purification and no additional purification for randomized oligonucleotides. However, we will provide the service upon request.