I was under the impression that HFBA would not cause contamination to LC tandem ESI-MS systems in negative mode from the recommendation of a few scientist. Unfortunately, after 4 years of pumping HFBA through our Aglient LC 1290 and Thermo Orbi trap, Negative mode is now heavily contaminated with HFBA related peaks. (surprisingly, it took until now to be an issue in negative mode)
Things I have tried:
16 hours of 1% formic in water flushed through LC and MS
Very warm water through LC
Clean the ESI source with MeOH:Water sonication
Can anyone recommend other solvents for removing the contamination?
In the future, I will likely try to switch to Formic acid for further Mobile Phase use.
You will need to shut down and thoroughly clean the ion optics and source; we have successfully used multiple washing (not just spraying, but immersion) to clean it out. Change your pump oil, discard your column and change out your tubing in the HPLC (all of it). All of the perflorinated compounds are absolute death on ESI- so avoid them like the plague. We also changed all of the optic and source seals, since perflorinateds like to hide in elastomeric material.
Hi everyone thanks for the feedback, our ion optics and source were all thoroughly cleaned during the annual preventive maintenance visit back in febuary as well as new pump oil, since that time, HFBA has not been used on the system.
I have replaced all PEEK tubing that was contaminated, but not the tubing for the mobile phase bottles or any seals associated with ESI source. I will look into that possibility as well as flushing with phases besides water and acids.
any other places the HFBA could be lurking? I am not sure I am equipped to replace seals on the mass spec side but know enough to work with the LC (aglient 1290) pieces.
I used to run our Agilent 1260 HPLC with TBAA (sticky ion pair) for 1-2 years. When this HPLC was connected to our new 6460 MS/MS system I realized that it was heavily contaminated with TBAA (I am not talking about the column, which was thrown away; I am talking about the PTFA-stainless steel tubings, fittings, seals, valves and everything throughout the HPLC). I could not get rid of TBAA completely even after flushing the system with several liters (>12L) of various solvents. I finally suspected the degasser, which was completely disassembled and the internal side of the vacuum chambers and its tubing were washed-soaked with acids, water and solvent. In my case, this procedure helped a lot. I suggest you to disconnect the degasser and check first if this is the main source of your contamination. Though, consider that disconnecting-connecting any PEEK fittings from the degasser may cause a surge of ion pair at the mass spectrometer (Ion pairs are hiding themselves between the outer surfaces of PEEK fittings and stainless steel ports. At least, that was my feeling). You have to be extremely patient and wait long enough to conclude if there is a reduction of ion pair signal or if it remains the same. Good luck!
"An Often Ignored HPLC & LC/MS Contamination Source. Did you check your Vacuum Degasser?"; https://hplctips.blogspot.com/2015/08/an-often-ignored-hplc-lcms.htm
- Inline vacuum degassers are also a huge source of contamination (when contaminated with ion pairing reagents). Often it goes unnoticed in a system with a UV/VIS detector, but when a MS detector is added, the amount of true contamination becomes known.
Ion pairing materials are not known to hide in-between any PEEK fitting unions. They are known to stick to the plastics used and that provides the source of continuous contamination. Replacement of tubing is recommended to reduce contamination.
As a matter of routine in such cases, throw out the contaminated column first. Next, always replace the solvent bottle pickup filters (esp if they are made from plastic) and all of the low pressure Teflon tubing from the bottles to the degasser and from the degasser to the gradient valve or pump head. The Teflon tubing is relatively inexpensive and often pickups additional contamination. If you clean everything else, but leave the tubing in place, any contamination present between the mobile phase bottles and the pump will continue to pollute your column.
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