Help needed on UPLC-MS carryover issue
Posted: Thu Aug 27, 2015 4:37 am
Hi people, I am currently using Waters Acquity UPLC coupled with TQS to study Plasmalogen (both phosphatidylcholine and phosphatidylethanolamine) and I am experiencing carryover issues when doing target profiling (MRM), such problem did not exist in global run. I've changed to a new column and the very first run had appearances of the carryover from previous plasmalogen samples, so i doubt the problem is with the column. Problem doesnt get any better despite washing ion source of MS.
Intensity decreased over blank injections, and peaks still appear when performed zero-volume injection.
100% ACN is used as strong wash and 95% H2O + 5% ACN is used as weak wash. Strong needle wash consists of 100% IPA and Weak needle wash consists of 90%H2O + 10% ACN. Mobile phase A is 40% H2O + 40% Methanol + 10% ACN while Mobile Phase B is 100% IPA. Other lipid compound studies uses same solvent composition and did not have carryover issue. So I think the problem is that the solvents are not that effective in getting rid of plasmalogen?
The column I am using now is Waters Acquity CSH C18 Microflow column, flow rate is set at 0.1mL/min and temp at 45 dC.
Not sure the problem lies with sample loop or unsuitable wash solvent? Hope some experts here can give me some suggestions.
Thanks in advance!
Intensity decreased over blank injections, and peaks still appear when performed zero-volume injection.
100% ACN is used as strong wash and 95% H2O + 5% ACN is used as weak wash. Strong needle wash consists of 100% IPA and Weak needle wash consists of 90%H2O + 10% ACN. Mobile phase A is 40% H2O + 40% Methanol + 10% ACN while Mobile Phase B is 100% IPA. Other lipid compound studies uses same solvent composition and did not have carryover issue. So I think the problem is that the solvents are not that effective in getting rid of plasmalogen?
The column I am using now is Waters Acquity CSH C18 Microflow column, flow rate is set at 0.1mL/min and temp at 45 dC.
Not sure the problem lies with sample loop or unsuitable wash solvent? Hope some experts here can give me some suggestions.
Thanks in advance!