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Malá Z, Gebauer P. Analytical isotachophoresis 1967–2022: From standard analytical technique to universal on-line concentration tool. Trends Analyt Chem 2022. [DOI: 10.1016/j.trac.2022.116837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Chen J, You X, Sun H, Tian J, Fang H, Xie J, Huang Y, Chen Z. Optimization of twin parallel microstrips based nuclear magnetic resonance probe for measuring the kinetics in molecular assembly in ultra-small samples. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:033106. [PMID: 33820024 DOI: 10.1063/5.0030452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 02/26/2021] [Indexed: 06/12/2023]
Abstract
We present the design, fabrication, characterization, and optimization of a TPM (twin parallel microstrip)-based nuclear magnetic resonance (NMR) probe, produced by using a low-loss Teflon PTFE F4B high frequency circuit board. We use finite element analysis to optimize the radio frequency (RF) homogeneity and sensitivity of the TPM probe jointly for various sample volumes. The RF homogeneity of this TPM planar probe is superior to that of only a single microstrip probe. The optimized TPM probe properties such as RF homogeneity and field strength are characterized experimentally and discussed in detail. By combining this TPM based NMR probe with microfluidic technology, the sample amount required for kinetic study using NMR spectroscopy was minimized. This is important for studying costly samples. The TPM NMR probes provide high sensitivity to analysis of 5 µl samples with 2 mM concentrations within 10 min. The miniaturized microfluidic NMR probe plays an important role in realizing down to seconds timescale for kinetic monitoring.
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Affiliation(s)
- Jiahe Chen
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, People's Republic of China
| | - Xueqiu You
- School of Information Engineering, Jimei University, Xiamen 361021, People's Republic of China
| | - Huijun Sun
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, People's Republic of China
| | - Jiaqin Tian
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, People's Republic of China
| | - Hongxun Fang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, People's Republic of China
| | - Junyao Xie
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, People's Republic of China
| | - Yuqing Huang
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, People's Republic of China
| | - Zhong Chen
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, People's Republic of China
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Swyer I, von der Ecken S, Wu B, Jenne A, Soong R, Vincent F, Schmidig D, Frei T, Busse F, Stronks HJ, Simpson AJ, Wheeler AR. Digital microfluidics and nuclear magnetic resonance spectroscopy for in situ diffusion measurements and reaction monitoring. LAB ON A CHIP 2019; 19:641-653. [PMID: 30648175 DOI: 10.1039/c8lc01214h] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
In recent years microcoils and related structures have been developed to increase the mass sensitivity of nuclear magnetic resonance spectroscopy, allowing this extremely powerful analytical technique to be extended to small sample volumes (<5 μl). In general, microchannels have been used to deliver the samples of interest to these microcoils; however, these systems tend to have large dead volumes and require more complex fluidic connections. Here, we introduce a two-plate digital microfluidic (DMF) strategy to interface small-volume samples with NMR microcoils. In this system, a planar microcoil is surrounded by a copper plane that serves as the counter-electrode for the digital microfluidic device, allowing for precise control of droplet position and shape. This feature allows for the user-determination of the orientation of droplets relative to the main axes of the shim stack, permitting improved shimming and a more homogeneous magnetic field inside the droplet below the microcoil, which leads to improved spectral lineshape. This, along with high-fidelity droplet actuation, allows for rapid shimming strategies (developed over decades for vertically oriented NMR tubes) to be employed, permitting the determination of reaction-product diffusion coefficients as well as quantitative monitoring of reactive intermediates. We propose that this system paves the way for new and exciting applications for in situ analysis of small samples by NMR spectroscopy.
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Affiliation(s)
- Ian Swyer
- Department of Chemistry, University of Toronto, 80 St George St., Toronto, ON M5S 3H6, Canada.
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Malá Z, Gebauer P. Recent progress in analytical capillary isotachophoresis. Electrophoresis 2018; 40:55-64. [DOI: 10.1002/elps.201800239] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 07/12/2018] [Accepted: 07/13/2018] [Indexed: 12/30/2022]
Affiliation(s)
- Zdena Malá
- Institute of Analytical Chemistry of the Czech Academy of Sciences; Brno Czech Republic
| | - Petr Gebauer
- Institute of Analytical Chemistry of the Czech Academy of Sciences; Brno Czech Republic
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Chen Y, Mehta HS, Butler MC, Walter ED, Reardon PN, Renslow RS, Mueller KT, Washton NM. High-resolution microstrip NMR detectors for subnanoliter samples. Phys Chem Chem Phys 2018; 19:28163-28174. [PMID: 29022609 DOI: 10.1039/c7cp03933f] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We present the numerical optimization and experimental characterization of two microstrip-based nuclear magnetic resonance (NMR) detectors. The first detector, introduced in our previous work, was a flat wire detector with a strip resting on a substrate, and the second detector was created by adding a ground plane on top of the strip conductor, separated by a sample-carrying capillary and a thin layer of insulator. The dimensional parameters of the detectors were optimized using numerical simulations with regards to radio frequency (RF) sensitivity and homogeneity, with particular attention given to the effect of the ground plane. The influence of copper surface finish and substrate surface on the spectral resolution was investigated, and a resolution of 0.8-1.5 Hz was obtained on 1 nL deionized water depending on sample positioning. For 0.13 nmol sucrose (0.2 M in 0.63 nL H2O) encapsulated between two Fluorinert plugs, high RF homogeneity (A810°/A90° = 70-80%) and high sensitivity (expressed in the limit of detection nLODm = 0.73-1.21 nmol s1/2) were achieved, allowing for high-performance 2D NMR spectroscopy of subnanoliter samples.
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Affiliation(s)
- Ying Chen
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99352, USA.
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Voeten RLC, Ventouri IK, Haselberg R, Somsen GW. Capillary Electrophoresis: Trends and Recent Advances. Anal Chem 2018; 90:1464-1481. [PMID: 29298038 PMCID: PMC5994730 DOI: 10.1021/acs.analchem.8b00015] [Citation(s) in RCA: 188] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Robert L C Voeten
- Division of BioAnalytical Chemistry, Department of Chemistry and Pharmaceutical Sciences, Vrije Universiteit Amsterdam , de Boelelaan 1085, 1081 HV Amsterdam, The Netherlands.,TI-COAST , Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Iro K Ventouri
- TI-COAST , Science Park 904, 1098 XH Amsterdam, The Netherlands.,Analytical Chemistry Group, van't Hoff Institute for Molecular Sciences, University of Amsterdam , Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Rob Haselberg
- Division of BioAnalytical Chemistry, Department of Chemistry and Pharmaceutical Sciences, Vrije Universiteit Amsterdam , de Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
| | - Govert W Somsen
- Division of BioAnalytical Chemistry, Department of Chemistry and Pharmaceutical Sciences, Vrije Universiteit Amsterdam , de Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
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