A fast sample shuttle to couple high and low magnetic fields and applications in high-resolution relaxometry

Combining high-resolution high-field nuclear magnetic resonance (NMR) with an evolution of spin systems at a low magnetic field offers many opportunities for the investigation of molecular motions and hyperpolarization and the exploration of field-dependent spin dynamics. Fast and reproducible transfer between high and low fields is required to minimize polarization losses due to longitudinal relaxation. Here, we introduce a new design of a sample shuttle that achieves remarkably high speeds ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:msub><mml:mi>v</mml:mi> <mml:mi>max</mml:mi></mml:msub> </mml:mrow> </mml:math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mo>∼</mml:mo></mml:math> 27 m s^-1). This hybrid pneumatic-mechanical apparatus is compatible with conventional probes at the high-field center. We show applications in water relaxometry in solutions of paramagnetic ions, high-resolution proton relaxometry of a small molecule, and sample shuttling of a solution of a 42 kDa protein. Importantly, this fast sample shuttle (FSS) system is narrow, with a diameter of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>d</mml:mi></mml:math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mo>=</mml:mo></mml:math> 6 mm for the sample shuttle container based on a standard 5 mm outer diameter glass tube, which should allow near access to the sample for magnetic manipulation at a low field.