title: Investigation of water environments in a C18 bonded silica phase using 1H magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy.
abstract: High resolution 1H magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectra have been obtained on typical C18 bonded silicas used in chromatographic solid-phase extraction separations. It has been shown for the first time that water molecules distributed in distinct physico-chemical environments within the chromatographic system can be detected directly using a simple 1H MAS NMR measurement. The resonances assigned to water protons in differing physico-chemical environments have distinct chemical shifts, line widths, relaxation times (T1 and T2) and also exhibit temperature dependent coalescence behaviour. This novel MAS approach may lead to a better understanding of the environments of other analytes in mixtures during such separations.
authors.affiliation: Biological Chemistry, Biomedical Sciences Division, Imperial College of Science, Technology and Medicine, Sir Alexander Fleming Building, South Kensington, London, UK SW7 2AZ.
authors.forename: M
authors.initials: M
authors.lastname: Coen
authors.forename: J C
authors.initials: JC
authors.lastname: Lindon
authors.forename: C
authors.initials: C
authors.lastname: Gavaghan
authors.forename: E
authors.initials: E
authors.lastname: Holmes
authors.forename: E
authors.initials: E
authors.lastname: Humpfer
authors.forename: I D
authors.initials: ID
authors.lastname: Wilson
authors.forename: P D
authors.initials: PD
authors.lastname: Stanley
authors.forename: J K
authors.initials: JK
authors.lastname: Nicholson