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Peaks in injected blanks but not in system blank

Question asked by jamesedwards on Apr 24, 2019
Latest reply on May 22, 2019 by jamesedwards

I am using an Agilent Infinitylab 1260 LC-MS trying to analyse three phospholipids - 16:0 Lysophosphatidylcholine, 16:0 Phosphatidylcholine and 16:0 Sphingomyelin


I have been having an issue with trying to do trace analysis on some samples and having peaks of the targeted compounds in my blanks at the retention times in the standard. I had put it down to contamination of the column which is a Zorbax SB-C18 column or myself contaminating my standards/blanks.


But I am finding though that when I do a system blank I get no peaks in my chromatogram which in my mind shows it isn't the column as I did think before. But when I injected fresh solvent which has not been near any of the targeted compounds that I see trace levels of the target compounds. I imagine this means it is something with the injector. I have seen that the injector has a continuous flow of mobile phase through it at all times when running so I guess it would not be carryover from the needle. Is there anything else I can try to do to check what could be causing it or have an idea of where it is coming from?