May 10th, 2007

Tattoo update

Oligo != Small Molecule

I work for a CRO in the oligo testing group. One of our clients is in Phase III and is preparing for final submission. A new client site taking over DP testing for the HPLC methods we developed. Today at our conference call, the group leader of the new site spent a good 20 minutes asking about the mobile phase preparation for the reverse phase method. Apparently, the main peak is eluting anywhere between 15 and 25 minutes into the 35 minute run. He doesn't understand what he's doing wrong and why the method isn't more robust. He then says that in his 16 years of doing small molecules, he's never had a problem with mobile phase prep. He is what he's doing and you tell me if you see something wrong here.

Measure 600mL H2O to a 1L graduated cylinder, begin stirring.
Using current cylinder to measure, add 350mL MeOH to the cylinder and stir for 30 min.
Using small cylinder to measure, add 45mL TEA to the cylinder and stir for 30 min.
Using volumentric pipette, add 5mL HFIP to cylinder and stir 60 min.
Filter and sonicate.

We regularly see the main peak elute somewhere between 17 and 22 minutes, but we've never seen 15 or 25. We keep telling him that oligos are extremely sensitive to organic solvents and ion pair reagents, but he doesn't seem to get it. He keeps thinking that everything should be as predictable as small molecules. This isn't a small molecule. It's not going to act like one. Get used to it.

And I don't know how he made it 16 years in industry without learning that you don't measure organics directly into water. He didn't mention using a hood or covering the cylinder. I hope he's doing both, but it's possible that he's doing neither.
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