Analysis of biofluids and chemical mixtures in non-deuterated solvents with1H diffusion-weighted PFG phase-sensitive double-quantum NMR spectroscopy

PFG NMR diffusion experiments for complex systems

“…DQDiff experiment is therefore phase sensitive, similar to other recently developed MQF diffusion experiments (8 ). The two significant advantages of phasesensitive detection over magnitude-mode detection are the following: 1) the retention of natural NMR line shapes, which preserves the spectral resolution, and 2) zero-average noise, which, unlike the all-positive noise of magnitude spectra, avoids the introduction of bias into spectral peak integrals.…”

Acceleration of 3D DOSY NMR by Spatial Encoding of the Chemical Shift

“…For conventional experiments three approaches exist: DOSYÀX, where a classic DOSY pulse sequence is followed by the chosen 2D pulse sequence (COSY, [4] DQS, HSQC…), X-DOSY, where the 2D pulse sequence is followed by the DOSY one, [8] and the iDOSY approach where the DOSY pulse sequence is integrated in the 2D pulse sequence. [5][6][7] Figure 1 shows two examples of COSY-DOSY pulse sequences. Any of these methods could in principle be implemented with spatial encoding of the indirect spectral dimension.…”

Multiple-Quantum NMR Studies on Molecular Mixtures

“…Dalvit et al [28] revisited this particular coherence order for the simplification of the spectra of mixtures. While DQ-1 H spectroscopy shares all the issues related to intensity dependence on the τ parameter, one of its main assets is that it provides a spectrum tantamount to COSY but without the nuisances linked to the presence of diagonal peaks.…”

“…In a first application of combined MQ and diffusometry to mixtures, Dalvit et al [28] incorporated diffusion-editing during the pumping period, to allow measurement of the diffusion coefficients using a 2Q correlation Figure 24 Comparison of 3Q-1Q correlation spectra recorded and processed with different US and NUS schemes. The sample was a mixture of aromatic compounds (phenol, o-terphenyl, dibenzyl, acetanilide, benzophenone, fluoranthene, naphthalene, anthracene, phenanthrene, triphenylene).…”

“…Thus, the relaxation term becomes a simple multiplicative factor, and a plot of Ln(I(τ 1 , τ 2 ) versus τ 3 1 + τ 3 2 À Á provides a linear decay allowing to determine D. This setup is perturbed, as all other NMR Figure 25 Pulse sequence for a diffusion-edited DQS as used in Ref. [28]. The gradients of variable intensity for encoding the diffusion decay are placed during the pumping period.…”