RF Microcoil Design for Practical NMR of Mass-Limited Samples

Subramanian, Raju; Lam, M. M.; Webb, Andrew

doi:10.1006/jmre.1998.1450

Cited by 61 publications

(40 citation statements)

References 5 publications

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“…The simulated numbers are derived from Eqs. [2]- [5] and from the effective coil resistances R c,eff that are obtained from electromagnetic simulations of the entire resonator circuit which includes the circuit model of the coil (Fig. 8) and those supplied by the capacitor vendors.…”

Section: Resultsmentioning

confidence: 99%

“…with a 5 80 ms and b 5 (200 ms) 2 to mathematically enhance resolution (RE). RE has only little effect on the FWHM linewidth (1.8 Hz instead of 1.9 Hz) but improves the line separation significantly.…”

Section: Resultsmentioning

confidence: 99%

“…As described in (1) and in other publications (2)(3)(4)(5), the main challenge of using microcoils is the low spectral resolution. Commonly, the linewidth LW is compromised by a nonhomogeneous distribution of the static magnetic field (B 0 -field) within the sample.…”

Section: Introductionmentioning

confidence: 90%

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Silicon cylinder spiral coil for nuclear magnetic resonance spectroscopy of nanoliter samples

Leidich

Braun

Geßner

et al. 2009

Concepts Magn Reson

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This contribution presents a new high sensitivity microdetector designed for high resolution proton NMR at 750 MHz (17.6 T) of sample volumes ranging from 5 to 40 nl. The desired volume of fluid is placed in a sealed 330/200 lm outer/inner diameter glass capillary and is then situated in the center of the detection coil. The high quality factor detection coils are fabricated using silicon microtechnology. The materials from which the device is constructed are specially shaped to improve the homogeneity of the static magnetic field within the sample. Adverse effects of the finite, nonspherical sample geometry on the spectral resolution are mitigated by employing sample rotation up to 2.5 kHz at the magic angle. The new detector exhibits linewidths of smaller than 3.0 Hz (0.004 ppm) and a signal-to-noise ratio in the spectral domain of higher than 4,000 per lmol of water. Results with respect to sensitivity, spectral resolution, and total sample volume are given and put into context with already published microprobes.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Silicon cylinder spiral coil for nuclear magnetic resonance spectroscopy of nanoliter samples

Leidich

Braun

Geßner

et al. 2009

Concepts Magn Reson

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“…Early published microcoil work utilized transceiver coils wound directly around and affixed to fused silica capillaries, yielding active volumes in the range of tens to hundreds of nanoliters (7). Other efforts showed the use of microcoils with static and sealed sample volumes from 4 to 15 lL (8, 9).…”

Section: Introductionmentioning

confidence: 99%

Design and construction of a microcoil NMR probe for the routine analysis of 20‐μL samples

Henry

Park

et al. 2008

Concepts Magn Reson

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Recent advances in microcoil NMR have provided commercially available, robust methodologies for analyzing mass and volume limited samples in the low microliter regime, and the technology has been applied in a number of areas. Unfortunately, due to constraints on sample size and the limited solubility of some compounds of interest, the application of this approach to certain areas of development, such as the structural analysis of chromatography eluates, is restricted. A current challenge is to provide an option within a previously unexplored sample size regime (tens of microliters) while still taking advantage of the increase in mass sensitivity afforded by solenoidal microcoil NMR. In this article, we present the design and construction of a microcoil NMR probe with a custom detection cell for the routine analysis of 20-lL samples. The detection cell is comprised of a CO 2 -laser-heated HF-etched borosilicate active volume with fused silica transfer lines added to provide sample input and output. This setup produces an enlarged sample bubble within the detection coil and provides easy connection with 1/16 in. standard LC connections, lending itself to applications with HPLC-NMR, online SPE and similar separation techniques, as well as higher-throughput robotic automation. NMR performance characteristics determined using standard compounds showed the probe exhibited reasonable resolution (<0.01 ppm), although sensitivity was less than optimal due to tuning constraints. Future improvements and opportunities are also discussed.

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“…One of the main challenges facing microfluidic NMR detection using microcoils is minimising line broadening due to magnetic susceptibility distortions. 6,7 The innovation of flat, linear radiofrequency stripline structures 8,9 is a promising design for reducing these distortions by (i) using a simpler topology (ii) orienting the inductor's axis parallel to the static field generated by the NMR magnet, (iii) being easily scalable to sample dimensions. The striplines make high-resolution spectroscopy possible on volumes of order 100 nL to a few μL, with sensitivities of 0.1 nanomole 1 H ffiffiffiffiffiffi Hz p .…”

mentioning

confidence: 99%

Analysis of mass-limited mixtures using supercritical-fluid chromatography and microcoil NMR

Tayler

Meerten

Kentgens

et al. 2015

Analyst

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RF Microcoil Design for Practical NMR of Mass-Limited Samples

Cited by 61 publications

References 5 publications

Silicon cylinder spiral coil for nuclear magnetic resonance spectroscopy of nanoliter samples

Silicon cylinder spiral coil for nuclear magnetic resonance spectroscopy of nanoliter samples

Design and construction of a microcoil NMR probe for the routine analysis of 20‐μL samples

Analysis of mass-limited mixtures using supercritical-fluid chromatography and microcoil NMR

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