[peptideismylife]

Hi,

I wanna deprotect two Alloc groups that are attached to two lysines on my peptide sequence. The peptide sequence is quite hydrophilic (contains Arg and Lys). I wanna do it in solution and not on the solid support and I am just worry about how can I get rid of the palladium catalyst before monitoring the reaction by LCMS.

I heard about that it is not nice to inject your sample containing Pd (can damage the column). Do u know any workup considering that my peptide is quite hydrophilic and I dont wanna lost anything....

Thanks!

[Doc Oc]

Put a small cotton plug at the bottom of a Pasteur pipet.  Add about 1/2 inch of Celite and pack it real good (the blunt end of a barbeque skewer works well for this).  Then take a 100-200 uL aliquot of your reaction (how much you take depends on how concentrated your reaction is) and squirt it on top of the Celite pad.  Add some acetonitrile and push it through the Celite into an HPLC vial.  You can take that vial directly to the machine for analysis.

[orgopete]

I am assuming the chromatography solvent is keeping the MS clean so no problem there (if someone knows whether this is wrong, please correct this assumption). Then it is a question of protecting the LC column. Two ways, filter all samples as Doc Oc suggested or guard column or per-filter. I lean more for speed and toss guard column or filter. If you take an LC aliquot, how much palladium will be in your sample?

If this is an open access machine, then follow the rules of the person that maintains it. If it is a group instrument, then it depends on whose time is most valuable, yours for filtering every sample or whether you can afford to toss a guard column every X injections.