I am running an Agilent 6410B QQQ with a 1200 LC front end, and I've been having great trouble trying to get rid of a contamination ion that appears to be suppressing my signal. The ion is at 113 m/z and from the breakdown products/knowing that it was used as a mobile phase modifier at 0.05% in Acetonitrile (Isocratic, for GPC) for an experimental method development, I know it is 1,4-diazabicyclo[2.2. 2]octane. I already know that this is not really compatible with an MS system and I have been struggling trying to flush it out of the system. It shows up as a constant background Ion and has greatly reduced sensitivity.
Here are the model numbers of all the units I am working with:
- G6410B QQQ
- G1315 DAD
- G1316A TCC
- G1367B HiP-ALS
- G1312A Bin Pump
- G1322A Degasser
I have flushed multiple times overnight and twice over the weekend with 100% IPA through the LC stack(50%A/50%B 0.2ml/min), as well as a 50/50 IPA/Water with 1% Formic Acid rinse overnight(0.2ml/min). Also multiple overnight flushes of ACN overnight and a Water flush overnight through both channels of the Degasser. (0.2ml/min)
I have removed and sonicated all of the parts in the source and flushed the source out as per Agilent's instructions multiple times, as well as replaced the Nebulizer needle and the Ion Capillary.
I have tried multiple brands of ACN (ACN 100% w/0.1% Formic Acid is the mobile phase I am trying to work towards) and have swapped out all solvent bottles for brand new ones from Agilent.
I am most of the way through completing Agilent's LC/MS Background Reduction Protocol as linked below, and I can see every other background Ion slowly going down in abundance, but the 113m/z peak is standing strong...
If anyone has any idea of where this contaminant could be hiding, please let me know so that I can move forward.