Quantitivity HSQC

More recently, an intensity-based, quantitative /method has been reported, which enables the determination of all endocyclic 111 homonuclear couplings in natural abundance carbohydrates of any molecular size.32 The proposed 2D 13C-COSMO-HSQC (cosine modulated heteronuclear single quantum correlation) relies on cosine modulation of XH magnetization with respect to all active homonuclear couplings as a preparation of HSQC. As a result, scalar couplings smaller than the natural line widths can be determined even in the presence of strong signal overlap. 

S units by quantitative NMR spectroscopy (Quantitative C NMR of Lignins section) or from 2D HSQC spectra (Quantification in 2D NMR section). Other differences between GS lignins are frequently the presence of unique entities, such as incorporated hydroxycinnamates (Ferulates in Lignins Cell Wall Cross-Linking in Grasses by Ferulates section), and y-acylated units (p-Hydroxybenzoates in Various Flardwoods section) [309]. 

Zhang, L. M., and GeUerstedt, G. (2007) Quantitative 2D HSQC NMR determination of polymer structures by selecting suitable internal standard references. Magn. Resort. Chem. 45(1), 37 5. 

Key Words Quantitative 2D NMR, 2D -resolved NMR, COSY, TOCSY, HSQC, 2D INEPT, Natural products, Metabolomics, Oil fractions. Food analysis. 

The loss of polarization is less severe in 2D INEPT compared to HSQC (cf. Figure 3). As Jhh seldom exceeds 10% of the /ch/ the effect of homonuclear coupling evolution to the quantitativity can be regarded as negligible in this particular case, but the error from this source should be understood when high precision in quantification is needed. 

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