What recommendations do you have on how to separate oligos tagged with an Alexa dye from any untagged oligos with HPLC?
We recommend using a buffer gradient. The different Alexa Dyes require slightly different gradient HPLCs to adequately separate tagged from untagged product. Our exact protocol is proprietary but running a gradient in the 75%A to 25% A range will get you started. We also suggest you NAP the oligo after the HPLC run.