This Information Applies To: Agilent LC/MS Systems
Contamination of the tune mix or the Calibrant Delivery System (CDS) of your LC/MS system can cause Autotune failures and drops in sensitivity due to ion suppression.
Contamination of the tuning or reference mix used on your LC/MS system can occur in several different ways. Diluted and undiluted mix can degrade over time, or due to extreme temperatures or storage conditions.
Often a large cluster of low molecular weight ions will overpower the tuning mix signal at low m/z, see Figure 1 for an example.
The process of diluting Tune Mix can also introduce contaminants from solvents, glassware, or pipette tips. Ensure the use of highest grade solvents and clean labware are used for the dilution process. One commonly seen contaminant is Polyethylene Glycol (PEG), which, can be seen as ions spaced regularly 44 amu apart. Figure 2 shows an example of PEG contamination on a G6546A Q-TOF.
Figure 2. And example of PEG contamination, with ions regularly spaced 44 amu apart
The following article details some more common contaminants found in LC-QQQ analysis and how to remove them for your LC-QQQ system: Troubleshooting LC-QQQ Contamination Issues
When experiencing contamination isolated to the tuning mix;
Contamination can also come from unexpected areas, such as nitrile gloves. Here are some general rules to minimize contamination from nitrile gloves:
If contamination persists, then please contact your local Agilent Service Representative.