Christie Hunter


How does Dynamic Ion Transmission Control (DITC) work on the TripleTOF systems?

Dynamic Ion Transmission Control (ITC) is the feature on all the QTOF systems from SCIEX where the MS ion current through the instrument is modulated scan by scan to ensure the detector saturation point is not reached. The modulation is done both at the level of total # of ions in a scan but also on the signal from a single peak if there is a dominant ion (like in a concentration curve at the high end). For each instrument, depending on the detection system, there is a TargetTIC that ITC modulates to maintain. In MS/MS mode, there is no ITC modulation of ion current as the Q1 isolation of analytes significant reduces ion load.

For assessing if in general you are running at too high a load for the detector from a total chromatogram perspective, the best way to do this is to look at where ITC is modulating.

First you need to make sure that Instrument Utilities is available for use in the software. Find the Instrument Utilities.dll in the C:\Program Files\AB SCIEX\PeakView 2\bin folder and make a copy of it and put it in the C:\Program Files\AB SCIEX\PeakView 2\Help Folder. Next time you open PeakView software, you will see Instrument Utilities in the drop down menu.

Open a datafile and extract out the TOF MS TIC in PeakView software. Select Instrument Utilities from the Help Menu and run Plot Count Conversion Factor. Adjust the y-axis to %. This new pane plots the % value that the ion transmission is getting modulated to. In this TripleTOF 6600 system example, you can see that in the most dense region of the chromatogram, the ITC is modulating to about 10%, therefore the instrument is not getting overloaded with signal.  If you see that that ITC is modulating down to around the 2% level for significant portions of the acquisition and you are doing experiments that require highly linear quantitation at the top end, you might want to consider loading less sample on your column.


Join the discussion

Comment below on this article and our team will answer your questions.


Submit a Comment