Removal of lipids contaminants from C18 column

Hi everyone,

Recently, I run the LCMS to analyze lipids (glycerol with 2 fatty acid chain, and 1 hydrophilic tail) with C18 column. I realized after running several times, the lipids are really stubborn, it sticks to the column. May I know what types of solvent can i use to remove this? I tried ACN, IPA (isocratic) but it seems not effective. Should I combine them?

Thank you.

  • You might make sure your sample does not come out of solution in the autosampler.  Analytes that collect in the tubing/equipment due to insolubility can be hard tor rinse from the system.  Maybe use starting mobile phase 100% methanol with 0.2% 5 M  ammonium acetate  in water and 100% isopropanol with 0.2% ammonium acetate in water for mobile phase B

    If compatible with the column, you could use 50% methylene chloride and 50% IPA to rinse the system.  Flush the system with IPA first and after to prevent immiscible solvent combinations.   I would not leave methylene chloride in the HPLC for an extended period since chlorinated solvents can be corrosive to stainless steel

  • You could always try 45% ACN:45% IPA:10% Acetone. Mix in one bottle and pump through column to waste. You don't want that in the MS! Make sure after flushing you then flush with more water miscible solvents like ACN then MeOH.

    Agree you may also have "stuff" stuck to tubing in the autosampler, so do some blank injections without a column to see what comes off the LC only.

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