Fit Graph

Analyse Function Curve Fitting to Peak Series Data

This popup is used to display the fit of a curve, of the displayed equation type, to data that has been extracted for a group of spectrum peaks from an NMR series. Precisely which kind of data is being fitted depends on the parent tool that this popup window was launched from. For example, for the Follow Intensity Changes tool the displayed graph is of a time or frequency value on the “X” axis (e.g. T1) verses peak intensity. For the Follow Shift Changes system the plot is for the parameters of the experiment titration on the “X” axis (e.g concentration) verses chemical shift distance.

The upper graph shows the peak data that was used; the blue points, and the points of the fitted theoretical curve; red points. The lower table lists the data points for all of the peaks in the group, to which the data relates. There will be one peak for each row of the table, and hence point on the “X” axis. For each data point in the table the corresponding peak from which the data was extracted may be located with the “Follow in window” option, using the stated spectrum window and making marker lines as desired. Alternatively, the peak may be viewed in a table with [Show Peak]

In general operation this system is used to check how well the selected function curve fits the peak data. The data that is displayed comes from the analysis tool that launched this popup. Any outliers may be removed using [Remove Point] (only with good reason) or the peaks themselves may be corrected if something has gone awry. Given that the display is launched from the selection of a specific group of peaks from a popup like Follow Shift Changes or Follow Intensity Changes and there are usually several peak groups that need to be analysed, the [Previous Set] and [Next Set] buttons can be used to quickly jump to the next peak group and see the next curve in the analysis results.

Main Panel

Scrollbar: :

pulldown Fitting Function: Selects which form of function to fit to the experimental data

pulldown Navigation Window: Selects which spectrum window will be used for navigating to peak positions

check Follow in window?: Whether to navigate to the position of the reference peak (for the group), in the selected window

check Mark Ref Peak?: Whether to put a multi-dimensional cross-mark through the reference peak position, so it can be identified in spectra

Table 1
Point The number of the data point, in order of increasing X-axis value
x For each point, the value of the parameter which is varied in the NMR series, e.g. T1, temperature, concentration etc.
y For each point, the experimental value being fitted, e.g. peak intensity of chemical shift distance
Fitted y The value of the best-fit function at the X-axis location
Δ The difference between the experimental (Y-axis) value and the fitted value

button Remove Point: Remove the selected data point, optionally removing the underlying peak

button Show Peak: Show a table of spectrum peaks that correspond to the selected data point

button Previous Set: Move to the previous set of fitted values; the next group of peaks, often corresponding to a different residue or resonance

button Next Set: Move to the next set of fitted values; the next group of peaks, often corresponding to a different residue or resonance

button Help: Show popup help document

button Close: Close popup

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Data Analysis : Follow Shift Changes

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