Multinuclear nanoliter one-dimensional and two-dimensional NMR spectroscopy with a single non-resonant microcoil

Abstract

Nuclear magnetic resonance (NMR) spectroscopy is a powerful analytical technique, but its low sensitivity and highly sophisticated, costly, equipment severely constrain more widespread applications. Here we show that a non-resonant planar transceiver microcoil integrated in a microfluidic chip (detection volume 25 nl) can detect different nuclides in the full broad-band range of Larmor frequencies (at 9.4 T from 61 to 400 MHz). Routine one-dimensional (1D) and two-dimensional (2D), homo-and heteronuclear experiments can be carried out using the broad-band coil set-up. Noteworthy, heteronuclear 2D experiments can be performed in a straightforward manner on virtually any combination of nuclides (from classical 1 H-13 C to more exotic combinations like 19 F-31 P) both in coupled and decoupled mode. Importantly, the concept of a non-resonant system provides magnetic fieldindependent NMR probes; moreover, the small-volume alleviates problems related to field inhomogeneity, making the broad-band coil an attractive option for, for example, portable and table-top NMR systems.

A broadband single-chip transceiver for multi-nuclear NMR probes

“…Recently, non-resonant microcoils were indicated as an option to realize volume-limited (25 nl) multi-nuclear NMR probes. 25 Nevertheless, at the same scale, it is still possible to use resonant micro-solenoids capable of high spectral resolution and spin sensitivity. 26 Indeed, when possible, the use of LC resonators allows a lossless intrinsic gain between the coil and the receiver, definitively advantageous in terms of SNR.…”

In vivo online magnetic resonance quantification of absolute metabolite concentrations in microdialysate

“…Micro-structured NMR/MRS probes have been fabricated in a variety of different geometries1516171819202122232425262728 and have partly been applied to continuous flow investigations2930 with solenoidal coils being the most sensitive to date1516. Utilizing this fact with the goal of online detection of metabolites at physiological concentrations for in vivo studies, we have constructed two different microprobes with solenoidal geometry: a 1 H-optimized probe tuned at 300 MHz and a 13 C-optimized probe with unprecedented sensitivity tuned at 50 MHz.…”

Determination of Kinetic Parameters within a Single Nonisothermal On-Flow Experiment by Nanoliter NMR Spectroscopy

“…21 −24 We have reported novel microfluidic chip designs for the monitoring of supramolecular interactions at the picomole level by 19 F NMR, 25 as well as multinuclear 1D and 2D NMR experiments with a single nonresonant microcoil. 26 In a previous paper, 27 we reported the use of a microfluidic NMR chip hyphenated to a continuous-flow microliter microwave irradiation system for online monitoring and rapid optimization of reaction conditions. The active volume of the NMR chip was chosen much smaller with respect to that of the microwave flow cell to allow the analysis of different zones of the reaction volume separately.…”