title: Determination of molecular self-diffusion coefficient  using multiple spin-echo NMR spectroscopy with removal of convection and background gradient artifacts.
abstract: A new approach is presented for the measurement of the self-diffusion coefficients of molecules in solution. It has been applied to metabolites in biofluids such as seminal and blood plasma at physiological temperature. The method is based on the double-gradient-spin-echo pulse sequence in which CPMG and bipolar gradient pulses have been implemented. The double-gradient spin-echo is shown to be useful in reducing the thermal convection that can cause over-estimation of the diffusion coefficients. The multiple spin-echoes in association with the CPMG approach is also insensitive to background gradient artifacts. In addition, the CPMG sequence enables longer diffusion periods (up to seconds) to be used without phase distortion; therefore, the proposed method is suitable for determining the diffusion coefficients of small metabolites in biofluids, where the resonances of large molecules, such as proteins, are suppressed during the spin-echo period as a result of their fast relaxation.
authors.affiliation: Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, People's Republic of China.
authors.forename: X
authors.initials: X
authors.lastname: Zhang
authors.forename: C G
authors.initials: CG
authors.lastname: Li
authors.forename: C H
authors.initials: CH
authors.lastname: Ye
authors.forename: M L
authors.initials: ML
authors.lastname: Liu
mesh_terms: D000596:Amino Acids / Q000032:analysis* / Q000097:blood; D016477:Artifacts; D004058:Diffusion; D004578:Electron Spin Resonance Spectroscopy; D005947:Glucose / Q000032:analysis*; D006023:Glycoproteins / Q000032:analysis* / Q000097:blood; D006801:Humans; D008074:Lipoproteins / Q000032:analysis* / Q000097:blood; D008297:Male; D012661:Semen / Q000737:chemistry
chemical_list: D000596:Amino Acids; D006023:Glycoproteins; D008074:Lipoproteins; D005947:Glucose