Hi CCPN users,
I have some trouble using the Rate Analysis function in Analysis
(Version 2.2. Release 1). I managed to setup an NMR series, fit a
function and look at the plots of the fits. The problem concerns the
I have a series of HSQC spectra that were recorded using different delay
times. In this case, we observe signals that increase with increasing
delay times. So the data that we want to fit is of the type (I selected
this type in Analysis)
A*exp(-Bx) + C
where B and C are positive, A is negative and the absolute value of C is
roughly equal to that of A
Now the problem is, that in the fit results Analysis only gets positive
values for A and negative values for B and C. So the fitting curve is
So the questions are basically: Is there a possibility to set starting
values for the parameters A,B and C or limited them to a certain range?
If no, is it possible to setup a custom equation, like -A*exp(-Bx) + C ?
To narrow down the problem:
If I choose some other equation (for example linear) I can see that
Analysis roughly gets the data fitted (as much as possible of course).
So the setup is ok, it's just that the fitting procedure is not getting
anywhere near the correct solution.
Also, I phase-shifted the spectra 180 degree to make everything
negative, since A and C should then switch sign. However the fitting
does not work any longer since the result list is complete empty. My
guess is that Analysis does not pick the peaks in the other HSQCs
anymore as they are now negative ( I did switch "Peak=> Peak Finding =>
Extrema to search for" to "positive and negative" ; that's how I created
the peak list at the first place )
Thank you and best regards,