Removal of lipids contaminants from C18 column

Question

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.

andyg · Answer

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

Removal of lipids contaminants from C18 column

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