Peak in the Target Ion Trace is not being integrated - WKB58711

SYMPTOMS

• The peak in the Target Ion Trace is not being integrated
• The peak in the Quantification Trace is integrated correctly
• The MRM transitions in the TargetLynx method and the MS method are confirmed to be the same
• The peak can be added manually but is not saved upon executing Save Peak Modifications
• The sample is a complex mixture with many peaks in the MRM trace
• When changing the Locate Peak Selection from Nearest to Largest, a peak is integrated in the Target Ion Trace, but it is the wrong peak

ENVIRONMENT

• MassLynx
• TargetLynx

CAUSE

The Retention Time Window settings are too wide, encompassing too many possible peaks.

FIX or WORKAROUND

1. Measure the width of the peak at the base in the Chromatogram view:
   • Open the chromatogram and display the specific MRM trace
   • Zoom in on in the peak of interest
   • Holding down the right mouse button, drag across the base of the peak
   • Continuing to hold the right mouse button, take note of the time shown in the lower-left corner of the Chromatogram view
2. Divide this number by 2 and add about 10%.
3. Enter this result into the Retention Time Window setting on the Compound Properties page of the TargetLynx method for this compound.
4. Set the Locate Peak Selection setting to Largest.
5. Reprocess the dataset.

ADDITIONAL INFORMATION

When trying to integrate peaks that are partially resolved, we recommend that you set the Retention Time Window for each individual compound to encompass the base of the peak plus just a little more. For peaks that are partially resolved, the RT Window should include the falling trace of the previous adjacent peak and/or the rising trace of the following peak, but not the apex of the adjacent peaks. This allows the integration to find the valley points between the partially resolved peaks. Set the Locate Peak Selection to Largest.