Transfer assignments and compare frequencies when peaks have moved

Instructions

When peaks have moved in a spectrum because of e.g. different experimental conditions, we might want to transfer the peak assignments from an earlier assigned set of peaks to the new peaks to follow the chemical shift changes. This is done by copying the assignments from the assigned peak list into a new unassigned peak list for the new experimental conditions.

Note: The safest way to move peaks is to first copy the assigned peaks list to a new peak list, and then move the peaks in the new peak list. In this way the two peak lists can be easily compared at a later stage. This copying is done by creating a empty “sister” peak list which we then copy the peaks into, in the {Peak Lists} tab of the Peak: Peak Lists popup (M: Peak: Peak Lists). Here we:

•     Select the Peak List to copy

•     Click [Add Sister List]

•     Click [Copy Peaks]

•     Select the “Sister” list as a destination list

A more detailed description about how to copy peaks lists and peaks is found here and here.

In this HowTo we will now show two ways in how to transfer assignments when peaks have moved:

• • Semi-automatically. Here we use the Assignment: Copy Assignment popup, accessible through M: Assignment: Copy Assignment. The procedure is described here.

  • Manually. Here we move the picked peaks in an earlier assigned peak list to the new peak positions. Make sure that both the peak list that has the assigned peaks and the peak list that has the unassigned peaks are displayed and active in the same window. For each peak we want to move, we then do as follow:

    • Select the peak

    • Move the mouse cursor position to the new local maxima

    • Click ‘p’ to move the peak

    • Click ‘P’ to snap the peak at the local maxima

    • The frequencies can be compared by clicking ‘d’ at the source peak position and draw the mouse cursor to the target peak position. The difference in frequency between the two peaks will then be shown in the upper right tab in the spectrum