I have a problem with peak tailing during LC-MS/MS. The weird thing is that it really depends on the sample I'm injecting. When I inject standard (mixture of 5 digested proteins) or any complex digests (whole yeast/HeLa) I have very nice symmetrical peaks. Now when I use exactly the same column setup for phosphopeptides after TiO2 enrichment (we are using lactic acid to increase selectivity and desalting on StageTips (with SDB-XC media)) peak shapes are terrible.
I do not know how to explain this?
I am using home made capillary columns (trap and analytical) packed with Phenomenex Jupiter 300A 3um C18 media.
I was wondering if anyone have had similar problems. Any ideas/suggestions are welcome.
Thank you,
Evgeny.