We generally see COSY artifacts in our HSQCs (at least for strong samples),
but I would suggest that they are actually a good artifact - they are small,
so you won’t confuse the COSY signals with real HSQC peaks, and when
you see them, it gives you good nearest neighbor connections. It’s like
getting H2BC data for free!
Walt
-------------------------------
Walter Massefski, Ph.D.
Director
Department of Chemistry Instrumentation Facility
Massachusetts Institute of Technology
77 Mass. Ave. Rm: 18-0090
Cambridge, MA 02139
T: (617) 253-2016
wwm_at_mit.edu <mailto:wwm_at_mit.edu>
> On Mar 3, 2026, at 4:37 PM, Anklin, Clemens via groups.io <clemens.anklin=bruker.com_at_groups.io> wrote:
>
> Hi Weixing
>
> HSQC's can show COSY type peaks when the acquisition time in the indirect
> dimension gets long. Would these peaks by any chance align with the C4 protons?
> The sequence hsqcedetgpsisp2.4 suppresses these COSY type artefacts.
>
> Clemens
>
> On 3/3/2026 2:38 PM, Zhang, Weixing via groups.io wrote:
>>
>> Dear Colleagues,
>> The attached picture shows the HSQC cross-peak of C3 and C5 in natural abundance β-glucose.
>> Coupling to the C2 and C4 protons makes C3 appear as a triplet, but I amunsure
>>what the small peak located ~32 Hz to the right of the main signal represents.
>> Similarly, for C5 there is also a small peak on the right side, approximately 20 Hz away from the main peak.
>> I would appreciate any insight into the origin of these additional peaks.
>> Thank you in advance.
>> Best regards,
>> Weixing
>>
>>
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Received on Wed Mar 04 2026 - 08:30:42 MST