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Köhler S, Nagl S, Fritzsche S, Belder D. Label-free real-time imaging in microchip free-flow electrophoresis applying high speed deep UV fluorescence scanning. LAB ON A CHIP 2012; 12:458-463. [PMID: 22011722 DOI: 10.1039/c1lc20558g] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report on label-free monitoring of microfluidic free-flow electrophoresis (μFFE) separations in real-time using a custom built high speed deep UV laser scanner. In combination with a novel layout realized in fused silica (FS) FFE chips the setup was successfully applied for continuous separations and detection of unlabeled analytes including native proteins by space-resolved intrinsic deep UV fluorescence scanning.
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Affiliation(s)
- Stefan Köhler
- Institute of Analytical Chemistry, University of Leipzig, Linnéstr. 3, 04103 Leipzig, Germany
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Köhler S, Weilbeer C, Howitz S, Becker H, Beushausen V, Belder D. PDMS free-flow electrophoresis chips with integrated partitioning bars for bubble segregation. LAB ON A CHIP 2011; 11:309-14. [PMID: 21060908 DOI: 10.1039/c0lc00347f] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
In this work, a microfluidic free-flow electrophoresis device with a novel approach for preventing gas bubbles from entering the separation area is presented. This is achieved by integrating partitioning bars to reduce the channel depth between electrode channels and separation chamber in order to obtain electrical contact and simultaneously prevent bubbles from entering the separation area. The three-layer sandwich chip features a reusable carrier plate with integrated ports for fluidic connection combined with a softlithographically cast microfluidic PDMS layer and a sealing glass slide. This design allows for a straightforward and rapid chip prototyping process. The performance of the device is demonstrated by free-flow zone electrophoretic separations of fluorescent dye mixtures as well as by the separation of labeled amines and amino acids with separation voltages up to 297 V.
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Affiliation(s)
- Stefan Köhler
- Institute of Analytical Chemistry, University of Leipzig, Linnéstr. 3, 04103, Leipzig, Germany
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YAMAMOTO C, SETO H, OHTO K, KAWAKITA H, HARADA H. Effect of .PI. Electrons on the Detection of Silver Ions by Ion-selective Electrodes Containing Tripodal Broom Molecules as an Ionophore. ANAL SCI 2011; 27:389. [DOI: 10.2116/analsci.27.389] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Chihiro YAMAMOTO
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University
| | - Hirokazu SETO
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University
| | - Keisuke OHTO
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University
| | - Hidetaka KAWAKITA
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University
| | - Hiroyuki HARADA
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University
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Liu CY, Qin DB, Leng XB, Chen LX, Zeng XS, Xu FB, Li QS, He XW, Zhang WQ, Zhang ZZ. Influences of hard donor on cation selectivities closing to soft selenium donor in tweezer-like calix[4]arene receptors. CHINESE J CHEM 2010. [DOI: 10.1002/cjoc.20040220808] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Fonslow BR, Bowser MT. Fast electrophoretic separation optimization using gradient micro free-flow electrophoresis. Anal Chem 2008; 80:3182-9. [PMID: 18351751 DOI: 10.1021/ac702367m] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The continuous nature of micro free-flow electrophoresis (mu-FFE) was used to monitor the effect of a gradient of buffer conditions on the separation. This unique application has great potential for fast optimization of separation conditions and estimation of equilibrium constants. COMSOL was used to model pressure profiles in the development of a new mu-FFE design that allowed even application of a buffer gradient across the separation channel. The new design was fabricated in an all glass device using our previously published multiple-depth etch method (Fonslow, B. R.; Barocas, V. H.; Bowser, M. T. Anal. Chem. 2006, 78, 5369-5374, ref 1). Fluorescein solutions were used to characterize the applied gradients in the separation channel. Linear gradients were observed when buffer conditions were varied over a period of 5-10 min. The effect of a gradient of 0-50 mM hydroxypropyl-beta-cyclodextrin (HP-beta-CD) on the separation of a group of 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) labeled primary amines was monitored as a proof of concept experiment. Direct comparisons to capillary electrophoresis (CE) separations performed under the same conditions were made. Gradient mu-FFE recorded 60 separations during a 5 min gradient allowing nearly complete coverage across a range of HP-beta-CD concentrations. In comparison, 4 h were required to assess 15 sets of conditions across the same range of HP-beta-CD concentrations using CE. Qualitatively, mu-FFE separations were predictive of the migration order and spacing of peaks in CE electropherograms measured under the same conditions. Data were fit to equations describing 1:1 analyte-additive binding to allow a more quantitative comparison between gradient mu-FFE and CE.
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Affiliation(s)
- Bryan R Fonslow
- University of Minnesota, Department of Chemistry, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, USA
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Stanković V, Duo I, Comninellis C, Zonnevijlle F. Silver electrowinning from silver(I)–calixarene complexes by two-phase electrolysis. J APPL ELECTROCHEM 2007. [DOI: 10.1007/s10800-007-9412-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Abstract
A micro-free-flow electrophoresis chip has been fabricated into a glass wafer etched with 20-microm-deep channels. Wafers were bonded anodically using an intermediate amorphous silicon film. Electric fields as high as 283 V/cm were applied across the separation channel to obtain baseline resolution of fluorescent standards in 4.8 s. The effect of electric fields ranging from 0 to 283 V/cm on the separations and resulting resolutions were examined. Resolution was shown to increase linearly with the applied electric field. Joule heating was not significant under the conditions tested. Instead, the generation of electrolysis products at higher currents proved to be the limiting factor preventing higher separation potentials from being used.
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Affiliation(s)
- Bryan R Fonslow
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, USA
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Fonslow BR, Bowser MT. Optimizing band width and resolution in micro-free flow electrophoresis. Anal Chem 2007; 78:8236-44. [PMID: 17165812 DOI: 10.1021/ac0609778] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The broadening mechanisms for micro-free flow electrophoresis (micro-FFE) have been investigated using a van Deemter analysis. Separation power, the product of electric field and residence time, is presented as a parameter for predicting the position of sample streams and for comparing separations under different conditions. Band broadening in micro-FFE is governed by diffusion at lower linear velocities and a migration distance-dependent mechanism at higher linear velocities. At higher linear velocities, the parabolic flow profile is elongated, generating a distribution of analyte residence times in the separation channel. This distribution of residence times gives rise to a distribution of migration distances in the lateral direction since analytes spend different amounts of time in the electric field. Equations were derived to predict the effect of electric field and buffer flow rate on broadening. Experimental data were collected to determine whether the derived equations were useful in explaining broadening caused by diffusion and hydrodynamic flow at different linear velocities and electric fields. Overall there was an excellent correlation between the predicted and experimentally observed values allowing linear velocity and electric field to be optimized. Suppression of electroosmotic flow is proposed as a means of reducing micro-FFE band broadening due to hydrodynamic effects and maximizing resolution and peak capacity.
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Affiliation(s)
- Bryan R Fonslow
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, USA
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Marcos PM, Félix S, Ascenso JR, Segurado MAP, Thuéry P, Mellah B, Michel S, Hubscher-Bruder V, Arnaud-Neu F. Complexation and transport of transition and heavy metal cations by p-tert-butyldihomooxacalix[4]arene tetraketones and X-ray crystal structure of the tert-butyl ketone derivative. NEW J CHEM 2007. [DOI: 10.1039/b705879a] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Electrical characterisation of calixarene-sensitive spin-coated layers. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2004. [DOI: 10.1016/j.msec.2003.11.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Ueda M, Saito T, Fujimori K, Moriuchi T, Shibutani Y. Potentiometric Performance of Silver Ion-Selective Electrodes Based on Tridentate Schiff Base Derivatives. ANAL SCI 2004; 20:1649-53. [PMID: 15636510 DOI: 10.2116/analsci.20.1649] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
To examine the directivity for improving the silver ion discrimination ability of a Schiff base, three kinds of tridentate ligands were synthesized and compared with the similar quadridentate ligand as the silver ionophore. Among the Schiff base derivatives tested, 3-(2-pyridylethylimino)-2-butanoneoxime, having one oxime and a pyridine substituent, was found to be the best ionophore for a silver-ion electrode. The electrode based on this derivative exhibited good silver-ion selectivity, -log Kpot(Ag+,K+) = 3.8, comparable to that of a quadridentate Schiff base, N,N'-bis(2'-hydroxyimino-1'-phenylpropyleden)-1,3-propanediamine, reported previously, except for a pseudo Nernstian response (35.6 mV decade(-1)) with a wide silver-ion activity change in the activity change from 5.0 x 10(-7) to 7.9 x 10(-2) mol dm(-3).
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Affiliation(s)
- Masato Ueda
- Department of Applied Chemistry, Faculty of Engineering, Osaka Institute of Technology, 5-16-1, Omiya, Asahi, Osaka 535-8585, Japan.
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Mahajan RK, Sood P, Mahajan MP, Singh P. 2,6-Bis-methylsulfanyl-[1,3,5]thiadiazine-4-thione as a Ag+-selective Ionophore. ANAL SCI 2004; 20:1423-6. [PMID: 15524195 DOI: 10.2116/analsci.20.1423] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A silver ion-selective electrode was prepared with a polymeric membrane incorporating 2,6-bis-methylsulfanyl-[1,3,5]thiadiazine-4-thione as an ionophore, tri-n-butylphosphate (TBP) as a plasticizer and sodium tetraphenylborate (NaTPB) as an additive. The electrode exhibited a near-Nernstian response of 52 mV/decade over a wide linear concentration range of 1.0 x 10(-5) - 1.0 x 10(-1) M with a lower detection limit of 9.77 x 10(-6) M. The electrode exhibited excellent selectivity for silver ion over many of the alkali, alkaline-earth and transition metal ions. The electrode worked well over a wide pH range of 1.77 - 7.13. The response time of the electrode was less than 20 s. The sensor can be applied as indicator electrode for the potentiometric titration of Ag+ ions with Cl- ions.
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UEDA M, KOMAI A, FUJIMORI K, MORIUCHI-KAWAKAMI T, SHIBUTANI Y. Evaluation of a dioxime-type Schiff base-poly (vinyl chloride) membrane as a silver-ion selective electrode. BUNSEKI KAGAKU 2002. [DOI: 10.2116/bunsekikagaku.51.779] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Masato UEDA
- Department of Applied Chemistry, Faculty of Engineering, Osaka Institute of Technology
| | - Akiyo KOMAI
- Department of Applied Chemistry, Faculty of Engineering, Osaka Institute of Technology
| | - Keiichi FUJIMORI
- Department of Applied Chemistry, Faculty of Engineering, Osaka Institute of Technology
| | | | - Yasuhiko SHIBUTANI
- Department of Applied Chemistry, Faculty of Engineering, Osaka Institute of Technology
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