Peak Selection & Integration
It’s possible to select peaks manually on chromatograms. But most of the time you’d want to set up an Integration Method for automatic detection. Additionally:
-
You can apply the same Integration Method to many injections at a time (aka batch processing)
-
And when using Peaksel On-Prem, it’s possible to configure different defaults for different instruments.
Integration Method settings
To set up the Integration Method, open any Injection, press i on the keyboard and change the settings.
After peaks are detected, and you like the results, you can apply the Integration Method to other Injections in the Batch.
SMOOTH
Smoothing is required to tell apart noise and real peaks. If the signal is noisy, you need to increase the level of smoothing. But too much smoothing can cause small peaks not detected. Additionally, the boundaries of peaks may get too wide. Make sure you check & uncheck Show smoothed to see how smoothing works.
Note, that smoothing determines only whether the peaks are detected and where the boundaries of the peaks are, but the area is calculated using the original (not smoothed) signal.
DETECT
We use an algorithm similar to Waters Empower ApexTrack. It relies on the 2nd derivatives - the sharper the peak, the more likely it’ll be detected.
Curvature threshold
Determines how sharp the peak has to be detected. Check Show 2nd derivative and ensure the dashed blue line intersects the apex of the 2nd derivative peak for it to be to be detected.
Note, that the more smoothing you applied, the smaller the 2nd derivative is going to be and the lower the Curvature threshold needs to be.