Electrochromatography in packed tubes using 1.5 to 50 μm silica gels and ODS bonded silica gels

Knox, John H.; GRANT, I

doi:10.1007/bf02321428

Cited by 480 publications

(232 citation statements)

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“…This phenomenon has been often observed by others and is attributed to local differences of the electroosmotic flow in the packing and frits [6,8,10]. Pressurizing the buffer vials is recommended to avoid the bubble formation [6,7,13] and this was applied by us (10 bar) but appeared to be ineffective. When reversing the polarity of the voltage, the same drying of the packing was observed but now at the terminal side of the column.…”

Section: Resultsmentioning

confidence: 61%

“…Further the electroosmotic flow depends only on the nature of the surface of the particles and is thus independent of the size of the channels. This means that in electrochromatography in principle reasonable flow rates can be generated on capillary columns length packed with sub-micron particles.In the last years the practical problems encountered with capillary electrochromatography (CEC), e.g., bubble formation and difficulties with the preparation of the terminal frits, have been solved satisfactorily [6][7][8][9][10] and the applicability of the technique with 3-5/am particles has been demonstrated now frequently [7,16]. So far only a few number of papers have been appeared dealing with smaller particles.…”

mentioning

confidence: 99%

“…So far only a few number of papers have been appeared dealing with smaller particles. Knox and Grant [6] and Yamamoto et.al [17] demonstrated CEC with nonporous silica particles of 1.6/am and Smith and Evans [7] used 1.8/am porous Zorbax particles. In this paper we report the results of an investigation to apply electrochromatography on capillaries packed with 1.5/am ODS modified non-porous silica particles.…”

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confidence: 99%

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Capillary electrochromatography with 1.5 μm ODS-modified non-porous silica spheres

et al. 1997

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SummaryThe particle realization of electrochromatography on capillaries packed with 1.5 /am ODS-modified nonporous silica spheres is demonstrated. In order to realize stable separation conditions it is crucial to add sodium dodecylsulphate (SDS) to the mobile phase and to pressurize both buffer vials at 10 bar. The presence of SDS stabilizes the current and makes the electro-osmotic flow in the packing more uniform so that no air bubbles are generated at high field strengths. The capillary columns are extremely efficient and on a 24 cm long column about 120,000 plates can be generated (a reduced plate height of about 1.3). The columns are very stable and no loss in efficiency was found after using a column continuously for two months.bolic. Further the electroosmotic flow depends only on the nature of the surface of the particles and is thus independent of the size of the channels. This means that in electrochromatography in principle reasonable flow rates can be generated on capillary columns length packed with sub-micron particles.In the last years the practical problems encountered with capillary electrochromatography (CEC), e.g., bubble formation and difficulties with the preparation of the terminal frits, have been solved satisfactorily [6][7][8][9][10] and the applicability of the technique with 3-5/am particles has been demonstrated now frequently [7,16]. So far only a few number of papers have been appeared dealing with smaller particles. Knox and Grant [6] and Yamamoto et.al [17] demonstrated CEC with nonporous silica particles of 1.6/am and Smith and Evans [7] used 1.8/am porous Zorbax particles. In this paper we report the results of an investigation to apply electrochromatography on capillaries packed with 1.5/am ODS modified non-porous silica particles. Attention will be given to the preparation of the column, the effect of the addition of SDS on the performance and the effect of the composition of the mobile phase on the efficiency. Illustrative chromatograms will be shown.

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Section: Resultsmentioning

confidence: 61%

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confidence: 99%

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confidence: 99%

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Capillary electrochromatography with 1.5 μm ODS-modified non-porous silica spheres

et al. 1997

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“…In this technique, on-column frits are required to retain the packing particles. There exist some problems associated with the frit making: frits prepared by polycondensation of potassium silicate and formamide 15 may cause some problems of permeability and chemical inertness.…”

Section: Introductionmentioning

confidence: 99%

Preparation of the Capillary-based Microchips for Solid Phase Extraction by Using the Monolithic Frits Prepared by UV-initiated Polymerization

2006

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A microfluidic solid phase extraction (SPE) array for sample enrichment was prepared by a simple method, a hot embossing technique. Five fused-silica capillaries (250 μm i.d., 380 μm o.d.) were partly embedded parallel in a polymethyl methacrylate (PMMA) microchip to serve as the extraction channels. Within each of the channels, a 2-mmlong monolithic porous polymer was prepared by in-situ photoinitiated polymerization. This then acted as the frit for packing of the extraction materials (octadecylsilica beads, ODS). By defining the light-exposure window on the channels, one can easily control the length and location of the polymer frits and the ODS beads can be packed at the desired location. With this method, solid phase extraction channels for microfluidic use can be easily prepared without complex fabrication of microstructures. Several SPE channels can be conveniently made in one microchip since the frits can be prepared in different channels through one polymerization; packing of the different channels can also be performed simultaneously. With the use of dilute ephedrine solutions, the sample loading capacity, linearity, and reproducibility were characterized. Coupled with the fast capillary electrophoresis separation, this microchip SPE array was applied for the detection of ephedrines in human urine.

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“…1(a) by the horizontal continuous line). 33 Regarding the interaction effect, CDP8779 control showed a very stable performance, with no significant and negligible predicted values in the three growing environments studied. Cambria had a similar performance but with a small instability (two significant G × E predicted effects).…”

Section: Prediction Of the Environmental Genotypic And Interaction Ementioning

confidence: 89%

Mejora de la calidad nutritiva del tomate: búsqueda de fuentes de variabilidad, estudio de la influencia del ambiente y determinación del control genético

Martínez¹,

María²

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AGRADECIMIENTOSEn el largo camino que llevo recorrido y que hoy llega a su fin con la defensa de esta tesis, he conocido a numerosas personas que de un modo u otro me han apoyado y que merecen un reconocimiento especial. Por ello agradezco:Al Ministerio de Ciencia e Innovación por concederme una subvención para un contrato de Técnico de Apoyo de Infraestructuras.A la Universitat Politècnica de València y al COMAV la concesión de una beca de Formación de Personal Investigador.A los doctores Salva Roselló y Fernando Nuez, directores de esta tesis, su apoyo incondicional y sus consejos a lo largo de las diversas etapas que han dado como resultado este manuscrito. En especial, agradecerle a Fernando la oportunidad de formar parte de esta gran familia de investigadores que es el COMAV, y a Salva, por adentrarme en el mundo de la mejora de la calidad y ayudarme a buscar la luz cuando me desesperaba porque la oscuridad no me dejaba avanzar en la investigación. Gracias por demostrarme que la paciencia y el buen hacer son imprescindibles para obtener trabajos de "calidad".Al Dr. José Manuel Herrero y a la Universitat de València, su aportación a la presente tesis. Gracias José, por ser tan accesible y brindarme la oportunidad de conocer una técnica de última generación.A la Dra. Merche Valcárcel y la Universitat Jaume I de Castelló, sin los cuales no se hubiera podido realizar la réplica de unos de mis trabajos más ambiciosos.Al Dr. Jaime Cebolla, que desde el primer día de esta tesis ha estado ahí, respondiéndome a las dudas y sin su apoyo algún que otro trabajo todavía no se habría publicado.Al Dr. Ángel Maquieira y al Departamento de Química por aceptarme como una más en los ratos que compartimos en el laboratorio, poniendo a mi alcance cualquier medio disponible.En especial, a Luis y a todos aquellos alumnos de Agrónomos y Agrícolas (en aquel entonces, mis niños) que mediante becas de colaboración, trabajos finales de carrera o créditos de libre elección compartieron conmigo inicialmente el día a día del laboratorio de mejora de la calidad: Ángeles, Dulce, Paco, Gloria, Luismi, Mercé, Víctor y Bibi.Y a los que han compartido conmigo este laboratorio al final, especialmente al Dr. Miguel Leiva y Carles Cortés. Gracias Miguel, por compartir recursos de una manera cordial y demostrar que si se quiere se puede. Gracias Carles, por nuestras charlas, tu alegría, tus ganas de trabajar y de competir, tu madurez, no cambies nunca… A mis compañeros del Banco de Germoplasma (Dra. María José, José Vicente, José, Eva, María, Marco y Quique), por su labor en la custodia y conservación de tantos tesoros, imprescindible para la elaboración de esta tesis.Al resto de mis compañeros del COMAV que tantos años me habéis sufrido y que tanto me habéis ayudado Jaume, Javi, Ali, Santi, María, Cristina, Cristina R., Estela, Juan Pablo, Julia, Carolina, Salva, Inma, Carmelo, Belén, Eva, José, Ximo, Carmina, Carlos, José María, Patri, Rosa, Ana, Olga, Iciar, Pascual, Carlos, Miguel Ángel, Paco, Ángel, Mariano, Salva, Mari Carmen, María José, Gl...

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Electrochromatography in packed tubes using 1.5 to 50 μm silica gels and ODS bonded silica gels

Cited by 480 publications

References 16 publications

Capillary electrochromatography with 1.5 μm ODS-modified non-porous silica spheres

Capillary electrochromatography with 1.5 μm ODS-modified non-porous silica spheres

Preparation of the Capillary-based Microchips for Solid Phase Extraction by Using the Monolithic Frits Prepared by UV-initiated Polymerization

Mejora de la calidad nutritiva del tomate: búsqueda de fuentes de variabilidad, estudio de la influencia del ambiente y determinación del control genético

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