I worked with 31P-1H HSQC to measure organic phosphorus compounds.
I always found unknown cross-signals resonating at places likely symmetrical to the strongest cross peaks about the diagonal. these unknown signals are quite strong but correpond to definitely nothing in relevant 1D spectra . does anyone have the same problem? A speactrum was attached.
the sequence is Varian VnmrJ built-in gHSQCAD. J1xh was set to 25 Hz. ni=128, ns=256.
Guess that it's not the lone one in the spectrum, though you may not have found those others! The problem can be part of impurity or on account of unconfirmed structure. The greases, solvent are other sources. The relevant signal to this is/are embedded in the spectra.
Hi Ruaz A, thanks for the input. I tried to run another HSQC spectrum, which can exclude the possibility of impurity or other factors.
The measured sample is a control sample containing a mixture of 2-aminoethyl phosphonic acid and methylenediphosphonic acid. It is supposed to give rise to three cross-signals at the lower-right corner. Correspondingly, however, three unknown signals shown up. Again, these unknown signals are likely symmetrical to the three cross-signals about the diagonal.
Specific parameters can be found in the 2nd page of the attached file.
Hi Dr. Anklin, high receiver gain is very much like the cause. Out of sudden, I remembered that there has been a problem with ADC since last week, before the 2D acquisition. Maybe the 2D exp. were somehow influenced already but we failed to notice that. Now I can finally relate together these two problems now. Danke sehr!
I extracted the first FID and it's flat baseline without signals at 8. 11 ppm and any other signals.
Could you please recommend relevant papers stating this kind of mirroring artifacts, or a handout?
Hi, Luming W, This could be caused by the faulty receiver as suggested by Clemens. A satellite kind of a signal (?)
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