title: Continuous Flow1H and13C NMR Spectroscopy in Microfluidic Stripline NMR Chips.
abstract: Microfluidic stripline NMR technology not only allows for NMR experiments to be performed on small sample volumes in the submicroliter range, but also experiments can easily be performed in continuous flow because of the stripline's favorable geometry. In this study we demonstrate the possibility of dual-channel operation of a microfluidic stripline NMR setup showing one- and two-dimensional1H,13C and heteronuclear NMR experiments under continuous flow. We performed experiments on ethyl crotonate and menthol, using three different types of NMR chips aiming for straightforward microfluidic connectivity. The detection volumes are approximately 150 and 250 nL, while flow rates ranging from 0.5 μL/min to 15 μL/min have been employed. We show that in continuous flow the pulse delay is determined by the replenishment time of the detector volume, if the sample trajectory in the magnet toward NMR detector is long enough to polarize the spin systems. This can considerably speed up quantitative measurement of samples needing signal averaging. So it can be beneficial to perform continuous flow measurements in this setup for analysis of, e.g., reactive, unstable, or mass-limited compounds.
authors.affiliation: Institute of Molecules and Materials, Radboud University , 6525 HP Nijmegen, The Netherlands.
authors.forename: Anna Jo
authors.initials: AJ
authors.lastname: Oosthoek-de Vries
authors.affiliation: Institute of Molecules and Materials, Radboud University , 6525 HP Nijmegen, The Netherlands.|Mesoscale Chemical Systems, MESA+ Institute of Nanotechnology, University of Twente , 7522 NB Enschede, The Netherlands.
authors.forename: Jacob
authors.initials: J
authors.lastname: Bart
authors.affiliation: Mesoscale Chemical Systems, MESA+ Institute of Nanotechnology, University of Twente , 7522 NB Enschede, The Netherlands.
authors.forename: Roald M
authors.initials: RM
authors.lastname: Tiggelaar
authors.affiliation: Institute of Molecules and Materials, Radboud University , 6525 HP Nijmegen, The Netherlands.
authors.forename: Johannes W G
authors.initials: JW
authors.lastname: Janssen
authors.affiliation: Institute of Molecules and Materials, Radboud University , 6525 HP Nijmegen, The Netherlands.
authors.forename: P Jan M
authors.initials: PJ
authors.lastname: van Bentum
authors.affiliation: Mesoscale Chemical Systems, MESA+ Institute of Nanotechnology, University of Twente , 7522 NB Enschede, The Netherlands.
authors.forename: Han J G E
authors.initials: HJ
authors.lastname: Gardeniers
authors.affiliation: Institute of Molecules and Materials, Radboud University , 6525 HP Nijmegen, The Netherlands.
authors.forename: Arno P M
authors.identifier: 0000-0001-5893-4488
authors.initials: AP
authors.lastname: Kentgens