Billion‐Fold Enhancement in Sensitivity of Nuclear Magnetic Resonance Spectroscopy for Magnesium Ions in Solution

Abstract

β-nuclear magnetic resonance (NMR) spectroscopy is highly sensitive compared to conventional NMR spectroscopy, and may be applied for several elements across the periodic table. β-NMR has previously been successfully applied in the fields of nuclear and solid-state physics. In this work, β-NMR is applied, for the first time, to record an NMR spectrum for a species in solution. (31)Mg β-NMR spectra are measured for as few as 10(7) magnesium ions in ionic liquid (EMIM-Ac) within minutes, as a prototypical test case. Resonances are observed at 3882.9 and 3887.2 kHz in an external field of 0.3 T. The key achievement of the current work is to demonstrate that β-NMR is applicable for the analysis of species in solution, and thus represents a novel spectroscopic technique for use in general chemistry and potentially in biochemistry.

Toward Applications of β-NMR Spectroscopy in Chemistry and Biochemistry

“…Thus, introduc- impact and applications ing various gases (He, Ar, and air) into the chamber, beam penetration and conservation of spin polarization during passage through the gas could be systematically tested as a function of gas pressure above the sample. The results were encouraging, demonstrating that a 61 keV 31 Mg + beam penetrates He gas in the sample chamber up to a pressure of about 0.1 mbar, and that the spin polarization is also preserved up to this pressure [5]. Although it is not quite sufficient to allow for an aqueous sample in the setup, it indicates that this should be possible with further development of the differential pumping system.…”

“…The experiments were successful, and resonance frequencies of 31 Mg implanted into a liquid sample were recorded, vide infra. The results of this pilot study have been published recently [5]. The project has clearly required the convergence of a broad spectrum of expertise from nuclear physics over engineering to biochemistry, the cross-fertilization that may occur more or less accidently when scientists from various fields are present at a large-scale facility, and a great, independent, and passionate effort by AG and MS. For future studies along these lines, beam times for 29,31 Mg and 58,74,75 Cu have been granted at ISOLDE-CERN [44, 45], and a proposal submitted to TRI-UMF (Canada) is pending technical issues.…”

“…impact and applications (some of which is conducted at large scale facilities ISOLDE [3], GANIL [6], RIKEN [7], TRIUMF [13]) [3][4][5][6][7][8][9][10][11][12][13][14]. In chemistry and biochemistry the advantages of β-NMR spectroscopy are: (1) high sensitivity, since as few as 10 5 -10 7 ions are required to record the signal and (2) access to chemical elements that are otherwise difficult to interrogate spectroscopically.…”

“…The sensitivity of β-NMR spectroscopy is further enhanced, as it is a radioisotope-based technique, exploiting the detection of anisotropic emission of β-particles from the spin polarized nuclei, vide infra, leading to a billion-fold or higher increase in sensitivity as compared to conventional NMR spectroscopy on stable isotopes. In addition to this, some of the elements which are problematic in conventional NMR spectroscopy, such as Mg, Ca, Cu, and Zn, already are or might be accessible with β-NMR spectroscopy [3][4][5]. Several applications of β-NMR spectroscopy in nuclear, solid state physics, and materials science have been published over the past decades [3][4][5][6][7][8][9][10][11][12][13][14] and references therein, and with the project described herein, we aim to advance the applications to solution chemistry and biochemistry [5].…”

CERN-MEDICIS (Medical Isotopes Collected from ISOLDE): A New Facility

“…In addition, the year 2012 was particularly successful for the biophysics collaboration, because a new apparatus allowing for β-NMR experiments on liquid samples was finally established at ISOLDE and tried in the world's first experiments in an ionic liquid. The results of this study will soon be published elsewhere [37].…”