TargetLynx peak integration shifts when you try to delete the peak - WKB46692

SYMPTOMS

• The mass chromatogram in TargetLynx has multiple peaks
• When you manually delete one of the integrated peaks, the integration shifts to a different RT
• If you delete the new integration, the integration shifts again to a different RT
• This integration may shift up to five or six times before it is finally deleted

ENVIRONMENT

• AutoSpec-P
• MassLynx 4.1
• TargetLynx

CAUSE

This is expected behavior. The reason for this behavior is that when anything changes (for example, peaks are deleted, the method is changed), we always relocate the peaks to ensure that the dataset is consistent. This is in case there has been chromatographic drift and a small peak located nearer the desired RT has been selected instead of the "real" peak. However, this behavior is more applicable to MRM type analyses, where the traces contain two peaks at the most. If one peak is deleted, the other one is used because that is then the best fit to the peak matching requirements set up in the method.

Unfortunately, this is not the ideal behavior when processing of AutoSpec data, where RT windows are wide and traces tend to contain lots of peaks.

FIX or WORKAROUND

Follow approach A or B:

A.

• Turn on the "Show All Peaks" option' (Display > Options > Chromatogram > Style > Show All Peaks).
• Right-click and choose "Delete All Peaks".

This deletes all the peaks on display in the selected chromatogram, so you need not do it multiple times.

B.
If the peaks are being deleted because they are too small, increase the Height Threshold on the Integration Parameters page of the method.

ADDITIONAL INFORMATION