Skip to main content
Waters

Peak Identification: Peaks Not Identified or Misidentified Due to Shifting Retention Times - Tip309

Article number: 251604

OBJECTIVE or GOAL

Address the issue where peaks are either not identified or misidentified due to shifting retention times.

ENVIRONMENT

  • Empower
  • Tip of the Week #309

PROCEDURE

STEP 1
The Processing Method is developed with a standard, and the peaks are named accordingly (Figure 1). 
Figure_1.png

STEP 2
We run a sample and see that there is a peak at 8.033 minutes that has a Peak Type Unknown. Peaks 3 and 4 display Peak Type Missing (Figure 2).
Figure_2.png

STEP 3
We know in this case that the peak at 8.033 minutes is Peak 3. Clicking the Show Components tool in the lower toolbar displays the expected retention time for Peak 3 and the RT window. The apex of this peak is outside of the window, resulting in "Peak Type Unknown" (Figure 3).
Figure_3.png

STEP 4
A possible solution is to increase the RT window. If the peak or peaks are well separated, you can increase the RT window (Figure 4).
Figure_4.png

There are three ways to do this:

  1. Change the RT window % value – this is a global parameter that will affect the RT window for all peaks.
  2. Change the RT window for an individual component in the table.
  3. Change the RT window for an individual component in the chromatogram by clicking the show components tool to display the window and moving either the start or end marker for the window. The table will update automatically.

STEP 5
The peak is now properly identified (Figure 5).
Figure_5.png
 

ADDITIONAL INFORMATION

This can be done with either the Pro or QuickStart interface.

Not able to find a solution? Click here to request help.