Hi everybody,
currently I observe quite frequently Cu-adducts on my ESI high resolution MS, especially when analyzing ligands. There was no Cu used for the synthesis, so it must come from the sample preparation and/or the analysis itself. There are two potential sources that come into my mind, the syringe, which is used for the sample injection and the solvent used for the analysis. I already tried different solvents, which did not change much.
Does anyone have some experiences with Cu-adducts in ESI MS and how to avoid it?
Thank you very much.
Michael
The gas lines which feed the ESI source should be made from 316 SS. I have observed cases at client sites where someone plumbed brass tubing or lines for the gases (which leads to contamination). Easy to check.
Please look at the following below links which may help you in your analysis:
http://www.rsc.org/suppdata/ra/c2/c2ra00961g/c2ra00961g.pdf
https://www.jbc.org/content/early/2001/02/27/jbc.M006554200.full.pdf
Thanks
You may also want to check your HPLC water supply. In-house, reverse osmosis (RO) ultra pure water generated from potable tap water is one of the best sources of high quality water for your LC methods. However, the water cartridges and system must be well maintained to deliver pure water. Most water supply pipes are copper. Metal contamination into a compromised water purification system might leach a small amount of metal ions into the water you use for LC-MS (It seems unlikely, but if you run out of ideas, maybe run a metal check on the water used).
Another possible source of copper could be from any plated metal parts in the flow path. These may corrode (some plated parts are plated over a base of pure copper). *Some client's use very strong acids in their mobile phase accelerating corrosion.
*HPLC (LC-MS) Vacuum degassers are a commonly overlooked cause of system contamination. We have observed severe corrosion inside HPLC vacuum degasser chamber modules (at the steel fittings) from use of strong acids (or from some ion pairing agents such as HFIP) which resulted in piles of residues, salts and oxides being deposited. These materials not only contaminate the vacuum system, but some can make their way into the flow path of the HPLC system resulting in column and/or detector contamination.
BTW: How do you know the "peak" is copper? Just based on mass alone? That is not proof.
Try do the troubleshoot the water by using the bottled HPLC water to see if it is the water issue. If the bottled water is good then use it and move on. The find the source of CU may be time consuming.
"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.html
- Badges
- Science topic