title: Back-exchange of deuterium in neutron crystallography: characterization by IR spectroscopy.
abstract: The application of IR spectroscopy to the characterization and quality control of samples used in neutron crystallography is described. While neutron crystallography is a growing field, the limited availability of neutron beamtime means that there may be a delay between crystallogenesis and data collection. Since essentially all neutron crystallographic work is carried out using D2O-based solvent buffers, a particular concern for these experiments is the possibility of H2O back-exchange across reservoir or capillary sealants. This may limit the quality of neutron scattering length density maps and of the associated analysis. Given the expense of central facility beamtime and the effort that goes into the production of suitably sized (usually perdeuterated) crystals, a systematic method of exploiting IR spectroscopy for the analysis of back-exchange phenomena in the reservoirs used for crystal growth is valuable. Examples are given in which the characterization of D2O/H2O back-exchange in transthyretin crystals is described.
authors.affiliation: Life Sciences Group, Institut Laue-Langevin, 71 avenue des Martyrs, Grenoble 38042, France; Faculty of Natural Sciences, Keele University, Keele ST5 5BG, UK.
authors.forename: Ai Woon
authors.initials: AW
authors.lastname: Yee
authors.affiliation: Large-Scale Structures Group, Institut Laue-Langevin, 71 avenue des Martyrs, Grenoble 38042, France.
authors.forename: Matthew P
authors.identifier: https://orcid.org/0000-0002-6412-4358
authors.initials: MP
authors.lastname: Blakeley
authors.affiliation: Life Sciences Group, Institut Laue-Langevin, 71 avenue des Martyrs, Grenoble 38042, France; Faculty of Natural Sciences, Keele University, Keele ST5 5BG, UK.
authors.forename: Martine
authors.initials: M
authors.lastname: Moulin
authors.affiliation: Life Sciences Group, Institut Laue-Langevin, 71 avenue des Martyrs, Grenoble 38042, France.
authors.forename: Michael
authors.initials: M
authors.lastname: Haertlein
authors.affiliation: Faculty of Natural Sciences, Keele University, Keele ST5 5BG, UK; European Synchrotron Research Facility, 71 avenue des Martyrs, Grenoble 38043, France.
authors.forename: Edward
authors.initials: E
authors.lastname: Mitchell
authors.affiliation: Life Sciences Group, Institut Laue-Langevin, 71 avenue des Martyrs, Grenoble 38042, France; Faculty of Natural Sciences, Keele University, Keele ST5 5BG, UK.
authors.forename: V Trevor
authors.initials: VT
authors.lastname: Forsyth
keywords: D2O/H2O back-exchange; IR spectroscopy; deuteration; neutron crystallography