When I acquire spectra of blood samples, NOESY spectra have humps in the alkyl region that make it difficult to analyze the spectrum. Is it better to use J-resolved or CPMG spectra to reduce or remove the hump?
8 February 2016 Comments Off on When I acquire spectra of blood samples, NOESY spectra have humps in the alkyl region that make it difficult to analyze the spectrum. Is it better to use J-resolved or CPMG spectra to reduce or remove the hump? FAQ - Sample Preparation
The large humps that you see in the NOESY spectra are due to macromolecules in the samples (mostly proteins and lipids). Alternative pulse sequences such as CPMG or J-resolved spectroscopy can help to remove these humps, but the effects of the proteins on the signals of small molecules will still be present. Most notably, you will need to adjust the linewidth of DSS or TSP to obtain reasonable fitting results, as both DSS and TSP bind to protein.
Note that our signature libraries have been calibrated to match the NOESY spectra and are not calibrated to the results from CPMG pulse sequences. While the results will be relative to other results in a particular study the actual values of the concentrations are not always accurate.
For more details on preparing blood serum and plasma samples for analysis using Chenomx NMR Suite, please refer to the user guide.
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