title: Use of glass capillaries to suppress thermal convection in NMR tubes in diffusion measurements.
abstract: Diffusion ordered spectroscopy (DOSY) is used to determine the translational diffusion coefficients of molecules in solution. However, DOSY is highly susceptible to spurious spectral peaks resulting from thermal convection occurring in the NMR tube. Thermal convection therefore must be suppressed for accurate estimation of translational diffusion coefficients. In this study, we developed a new method to effectively suppress thermal convection using glass capillaries. A total of 6 to 18 capillaries (0.8-mm outer diameter) were inserted into a regular 5-mm NMR tube. The capillaries had minimal effect on magnetic field homogeneity and enabled us to obtain clean DOSY spectra of a mixture of small organic compounds. Moreover, the capillaries did not affect chemical shifts or signal intensities in two-dimensional heteronuclear single quantum coherence spectra. Capillaries are a simple and inexpensive means of suppressing thermal convection and thus can be used in a wide variety of DOSY experiments. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto, 619-0284, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Iwashita
authors.affiliation: Department of Structural and Chemical Biology, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Konuma
authors.affiliation: Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto, 619-0284, Japan.
authors.forename: Erisa
authors.initials: E
authors.lastname: Harada
authors.affiliation: Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto, 619-0284, Japan.
authors.forename: Shoko
authors.initials: S
authors.lastname: Mori
authors.affiliation: Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku Katsura, Nishikyo-Ku, Kyoto, 615-8510, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Sugase
keywords: 1H NMR; Capillary; DOSY; NMR; thermal convection