What does the "!" mean in the centroided MassLynx mass spectrum from a QTof? - WKB108561
Article number: 108561
ENVIRONMENT
- Tof (time-of-flight) instruments
- MassLynx 4.1
- MassLynx 4.2
ANSWER
The "!" means that the centroided MS peak on the MassLynx mass spectrum has a shape or resolution suggesting that interference may have occurred.
You would expect to find MS peaks flagged with an exclamation mark, "!", around the electronic noise level of a mass spectrum or a low LCMS background mass spectrum. However, it is a concern when an MS base signal, very distinctive from the electronic noise or LCMS background ions, is flagged this way.
When a true component or base signal has the ! peak flag, quite often this means that the mass spectral resolution on the peak has deteriorated. The best solution is to retune the resolution, save the settings, re-calibrate and run the acquisition again.