Peak Identification: Peaks Not Identified or Misidentified Due to Shifting Retention Times - Tip309
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).
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).
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).
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).
There are three ways to do this:
- Change the RT window % value – this is a global parameter that will affect the RT window for all peaks.
- Change the RT window for an individual component in the table.
- 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).
ADDITIONAL INFORMATION
This can be done with either the Pro or QuickStart interface.