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When I used the automatic peak picking function of Topspin for picking the cross peaks in a 1H-15N HMBC spectrum, two cross peaks were observed very close to each other (8.12,252.78 and 8.13,253.17). However, in the 1D projection of the 15N channel of the same spectrum, only one peak is being shown at 252.78. Should the cross peak values be taken into consideration or should the 1D projection values be taken into consideration?

asked Nov 25 '14 at 23:48

Bhanu's gravatar image


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It's a matter of resolution. I can't answer directly on your question, bur generaly one should pay more attention to the crosspeaks than to projection, because projection is a sum of whole row, some signals could be nullified.

If you want to be sure, just try to make this experiment with two times more points in F1 (TD1) or try to use Linear prediction in this dimension - it will help with resolution and maybe it will clarify your concerns.


answered Nov 26 '14 at 01:35

Arkadiusz%20Leniak's gravatar image

Arkadiusz Leniak

Thanks for your answer. I will try to use Linear prediction and see the results. - Bhanu (Nov 26 '14 at 04:23)

In case of 1H-15N HMBC (It's a majority of my NMR work) linear prediction works the best when you double points (TD1) from experiment (for example you obtained 512 transients, so use linear prediction to make 1024, use points from 2-512, and coeficient as a 3 times of all signals on spectrum. - Arkadiusz Leniak (Nov 26 '14 at 05:10)

Thank you. Followed your suggestions and it helped. - Bhanu (Nov 27 '14 at 20:23)

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