Peak picking

There are two main ways to pick peaks in CcpNmr: (1) automatic and (2) manual peak picking.

Automatic method

The easiest approach is to let the software decide which signals are peaks and position their maxima automatically. In order to do so, in window1, hold down the Shift and Ctrl keys while dragging around an area with the left button of the mouse pressed. Once you release the left button, CcpNmr will find the contour extrema and define them as peaks.

As you can see from the image above, several peaks were placed on signals that are likely corresponding to noise. Hence while using the automatic method, you need to make sure your contour levels are appropriate in order to prevent picking peaks from the noise!

A visual inspection is highly recommended following the procedure. In order to delete unwanted peaks, you can select one peak (or multiple peaks by holding the Shift button while selecting the peaks) by left-clicking on the peak of interest, and then pressing the Delete key, then accepting the deletion.

Manual method

Sometimes, you want to pick peaks manually, or want to add a second peak mark over a signal representing overlapping peaks. To do so, hold down the Ctrl key and left-click on the location where you want to pick a peak. A cross will appear.

You can then move it while it is being selected by moving the mouse to the appropriate location and press the p key. You may even be able to center it in the peak signal by pressing Shift + p.

Inspecting the peak list

A table containing a list of peaks for each spectrum can be found here: Peaks > Peak Lists and select the Peak Table tab. In that table, you will find information about each peak (position, assignment, height and volume, etc.).

You can also export the information in a text file by right-clicking in the table and selecting Export.

Next step

In the step, we will go over setting up a project and assigning root resonances.