Using indirect covariance spectra to identify artifact responses in unsymmetrical indirect covariance calculated spectra

  title={Using indirect covariance spectra to identify artifact responses in unsymmetrical indirect covariance calculated spectra},
  author={Gary E. Martin and Bruce D. Hilton and Kirill A. Blinov and A. J. Williams},
  journal={Magnetic Resonance in Chemistry},
Several groups of authors have reported studies in the areas of indirect and unsymmetrical indirect covariance NMR processing methods. Efforts have recently focused on the use of unsymmetrical indirect covariance processing methods to combine various discrete two‐dimensional NMR spectra to afford the equivalent of the much less sensitive hyphenated 2D NMR experiments, for example indirect covariance (icv)‐heteronuclear single quantum coherence (HSQC)‐COSY and icv‐HSQC–nuclear Overhauser effect… 
13 Citations

Multistep correlations via covariance processing of COSY/GCOSY spectra: opportunities and artifacts

Results obtained from covariance‐processed GCOSY spectra are fully analyzed and compared to normally processed COSY and 80 ms TOCSY spectra and the origin of artifact responses is analyzed.

Homo- and Hetero-Covariance NMR Spectroscopy and Applications to Process Analytical Technology

Covariance processing of data and spectra has established itself among the computerbased NMR spectroscopy methodologies to increase sensitivity and resolution and to facilitate spectral analysis.

Web server suite for complex mixture analysis by covariance NMR

A suite of public web servers, termed COLMAR, is presented, which facilitates complex mixture analysis by NMR, and examples are presented that illustrate the utility of this web server suite forcomplex mixture analysis.



Analysis and elimination of artifacts in indirect covariance NMR spectra via unsymmetrical processing

Using an IDR (inverted direct response)‐HSQC‐TOCSY spectrum as a starting point for the indirect covariance processing, a spectrum that can be described as a carbon–carbon COSY experiment is obtained, and data are analogous to the autocorrelated 13C–13C double quantum INADEQUATE experiment except that the direct covariance NMR spectrum establishes carbon– carbon connectivities only between contiguous protonated carbons.

Application of unsymmetrical indirect covariance NMR methods to the computation of the 13C↔15N HSQC‐IMPEACH and 13C↔15N HMBC‐IMPEACH correlation spectra

Correlations for carbon resonances long‐range coupled to a protonated carbon in the 1H13C HMBC spectrum are transferred via the long-range 1H 15N coupling pathway in the1H15N IMPEACH spectrum to afford a much broader range of correlation possibilities in the 13C15N HMBC‐IMPEACH correlation spectrum.

Utilizing unsymmetrical indirect covariance processing to define 15N13C connectivity networks

The utilization of unsymmetrical indirect covariance NMR methods for the combination of 1H13C GHSQC and 1H 15N long‐range (GHMBC, IMPEACH‐ MBC, CIGAR‐HMBC, etc.) heteronuclear chemical shift correlation spectra to determine 15N13C correlation pathways is reported.

Using unsymmetrical indirect covariance processing to calculate GHSQC-COSY spectra.

GHSQC-TOCSY experiments allow sorting of proton-proton connectivity information as a function of (13)C chemical shift, which is of significantly lower sensitivity and the data require considerably more time to acquire than either of the component experiments.

Unsymmetrical covariance processing of COSY or TOCSY and HSQC NMR data to obtain the equivalent of HSQC‐COSY or HSQC‐TOCSY spectra

Artifacts observed in the indirect covariance NMR spectrum of HSQC-TOCSY data have recently been analyzed and a method for their elimination proposed. More recently, unsymmetrical covariance

The use of unsymmetrical indirect covariance NMR methods to obtain the equivalent of HSQC‐NOESY data

The application of the unsymmetrical indirect covariance NMR methods to the combination of HSQC and NOESY spectra is demonstrated to provide results comparable toHSQC‐NOESY data, albeit with greater sensitivity and with considerably less spectrometer time.

Long‐range carbon–carbon connectivity via unsymmetrical indirect covariance processing of HSQC and HMBC NMR data

Using experimentally discrete HSQC and HMBC data sets, it is shown that unsymmetrical indirect covariance processing of the pair of NMR spectra affords a presentation containing long‐range carbon–carbon connectivity information.

13C-15N Connectivity networks via unsymmetrical indirect covariance processing of 1H-13C HSQC and 1H

Long-range 1H-15N heteronuclear shift correlation methods at natural abundance to facilitate the elucidation of small molecule structures have assumed a role of growing importance over the past

Homonuclear long‐range correlation spectra from HMBC experiments by covariance processing

The method, which identifies correlated spin networks in terms of covariance between one‐dimensional traces from a single decoupled HMBC experiment, derives 13C�13C as well as 1H1H spin connectivity maps from the two‐dimensional frequency domain heteronuclear long‐range correlation data matrix.

Indirect covariance NMR spectroscopy.

A novel NMR scheme is presented that establishes homonuclear spin correlations without requiring direct detection of the spin species, which opens up new avenues for the experimental analysis of molecules containing insensitive spins encountered in biomolecular NMR and analytical chemistry including metabolomics.