Some time ago I had asked whether one could manually "follow" a peak during
a titration if it wasn't picked up correctly using 'group peaks' under
"follow peak changes".
Tim answered 'it is certainly possible', but after a lot of fiddling around
I am still very confused about it.
How do I exactly go about doing this?
My understanding is that the "follow shift changes" dialog ('Group Peaks')
works as follows:
1. it makes sure that each spectrum in the series is assigned its own shift
list (and complains if it's not the case)
2. it reads the assignment of the first peak in the reference spectrum
3. it finds the corresponding, shifted peak in the first experiment of the
series based on the specified error/isotope weight/step size/gradient
4. it assigns that peak automatically and adds the information to the (new)
shiftlist of that spectrum
5. rinse and repeat for each peak in each experiment of the series.
Am I on track so far?
Now, let's say I want to *manually* assign a peak because its shift was not
"followed" properly by the 'group peaks' routine. If I select the peak and
hit 'assign', I will usually find that a resonance for this peak or rather
its correspondent peak in the reference spectrum already exists (at least in
one dimension) at a slightly different chemical shift.
But what should I do now?
Option A.
Select *that* existing, assigned resonance and apply it to the shifted peak
(assuming that analysis will 'copy' it to the separate shiftlist of that new
spectrum)
or
Option B. Create a new resonance and assign it (making a new assignment for
an existing atom, but making sure to - manually - select the new shiftlist,
not the one for the reference spectrum.
I thought that option B was the way to go, but I have several issues with it.
- I'm worried about messing up my original shift list (which I certainly
don't want to do!!) since there's no feedback or confirmation
- I have to remember *by heart* which titration spectrum (step) goes with
what shiftlist number - it's not indicated in the assignment window!
- I end up with the same assignment TWICE for different resonances, again
without an annotation of "which goes with which"
Of course it only gets worse and more confusing if I repeat that for the
other spectra in the experiment series!
Wouldn't a much simpler and less confusing way be to select a peak 'group'
(peak in reference spectrum + all titration spectra) and directly
*propagate* the assignment across the entire titration series?
Analysis could then simply write these assignments into their respective
shift lists and Bob's your uncle.
Am I missing something crucial here?
Two other quick comments (not a complaint, just to give feedback)
- analysis still quits immediately (segmentation fault) when I select the
Ax/(1+Ax) fit function
- 'peak groups' that are not assigned to at least 1 spectrum in the
experiment series (reference spectrum not included) cannot be deleted (I
have to revert to a backup of my project to 'fix' it).
Many thanks, as always!
Martin
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