Impact of Conduit Geometry on the Performance of Typical Particulate Microchip Packings

Jung, Stephanie; Höltzel, Alexandra; Ehlert, Steffen; Mora, Jose-Angel; Kraiczek, Karsten; Dittmann, Monika; Rozing, Gerard P.; Tallarek, Ulrich

doi:10.1021/ac902069x

Cited by 32 publications

(19 citation statements)

References 43 publications

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“…increasing lateral equilibration distance for velocity heterogeneities). This behaviour agrees with the experimental trend observed by Jung et al [21] for longitudinal dispersion in particulate microchip packings contained in channels of different cross-sectional geometries, where dispersion was found to increase with decreasing conduit symmetry (at similar bed porosity).…”

Section: (B) Transient Longitudinal Dispersionsupporting

confidence: 92%

“…The circular packing has a diameter of 20d p , the side lengths of the rectangular packing are 25 and 12.5d p , and the radius of the semicircular packing is 14.1d p . The packing dimensions and porosity were chosen to reflect the conduit-to-particle-size ratios and relatively dense packings of the chromatographic beds used in capillary and microchip separations [21]. The lateral porosity distributions (figure 1b) reveal that particles are highly ordered in the near-wall region; the sphere centres of the first particle layer from the wall form a sharply defined line.…”

Section: Resultsmentioning

confidence: 99%

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Transient and asymptotic dispersion in confined sphere packings with cylindrical and non-cylindrical conduit geometries

Khirevich

Höltzel

Tallarek

2011

Phil. Trans. R. Soc. A.

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We study the time and length scales of hydrodynamic dispersion in confined monodisperse sphere packings as a function of the conduit geometry. By a modified Jodrey-Tory algorithm, we generated packings at a bed porosity (interstitial void fraction) of 3 = 0.40 in conduits with circular, rectangular, or semicircular cross section of area 100pd 2 p (where d p is the sphere diameter) and dimensions of about 20d p (cylinder diameter) by 6553.6d p (length), 25d p by 12.5d p (rectangle sides) by 8192d p or 14.1d p (radius of semicircle) by 8192d p , respectively. The fluid-flow velocity field in the generated packings was calculated by the lattice Boltzmann method for Péclet numbers of up to 500, and convectivediffusive mass transport of 4 × 10 6 inert tracers was modelled with a random-walk particle-tracking technique. We present lateral porosity and velocity distributions for all packings and monitor the time evolution of longitudinal dispersion up to the asymptotic (long-time) limit. The characteristic length scales for asymptotic behaviour are explained from the symmetry of each conduit's velocity field. Finally, we quantify the influence of the confinement and of a specific conduit geometry on the velocity dependence of the asymptotic dispersion coefficients.

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Section: (B) Transient Longitudinal Dispersionsupporting

confidence: 92%

Section: Resultsmentioning

confidence: 99%

Transient and asymptotic dispersion in confined sphere packings with cylindrical and non-cylindrical conduit geometries

Khirevich

Höltzel

Tallarek

2011

Phil. Trans. R. Soc. A.

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“…A number of important parameters and their often-complex influences were identified and correlated with the separation efficiency. These include the width and shape of the particle size distribution (PSD) and surface properties of the particles [6, 11], the inner diameter of capillary columns [12], the conduit geometry, in particular, of HPLC microchips [25, 26], and the slurry concentration [2, 13]. Modern three-dimensional (3D) imaging techniques provide insights into the relationship between morphological properties of porous materials and their performance in targeted applications [27–31].…”

Section: Introductionmentioning

confidence: 99%

Bed morphological features associated with an optimal slurry concentration for reproducible preparation of efficient capillary ultrahigh pressure liquid chromatography columns

Reising

Godinho

Jorgenson

et al. 2017

Journal of Chromatography A

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Column wall effects and the formation of larger voids in the bed during column packing are factors limiting the achievement of highly efficient columns. Systematic variation of packing conditions, combined with three-dimensional bed reconstruction and detailed morphological analysis of column beds, provide valuable insights into the packing process. Here, we study a set of sixteen 75 µm i.d. fused-silica capillary columns packed with 1.9 µm, C18-modified, bridged-ethyl hybrid silica particles slurried in acetone to concentrations ranging from 5 to 200 mg/mL. Bed reconstructions for three of these columns (representing low, optimal, and high slurry concentrations), based on confocal laser scanning microscopy, reveal morphological features associated with the implemented slurry concentration, that lead to differences in column efficiency. At a low slurry concentration, the bed microstructure includes systematic radial heterogeneities such as particle size-segregation and local deviations from bulk packing density near the wall. These effects are suppressed (or at least reduced) with higher slurry concentrations. Concomitantly, larger voids (relative to the mean particle diameter) begin to form in the packing and increase in size and number with the slurry concentration. The most efficient columns are packed at slurry concentrations that balance these counteracting effects. Videos are taken at low and high slurry concentration to elucidate the bed formation process. At low slurry concentrations, particles arrive and settle individually, allowing for rearrangements. At high slurry concentrations, they arrive and pack as large patches (reflecting particle aggregation in the slurry). These processes are discussed with respect to column packing, chromatographic performance, and bed microstructure to help reinforce general trends previously described. Conclusions based on this comprehensive analysis guide us towards further improvement of the packing process.

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“…However, in these microchip devices, phosphopeptide enrichment components are usually fabricated by packing functionalized particles, such as TiO 2 or IMAC beads, into microchannels. It is worth to note that the packing process in microchannels is more complex and difficult when compared to that with capillary columns [21]. Moreover, fabrication of frits or incorporation of a physical barrier is required to trap particles in chip channels, leading to high cost and poor reproducibility.…”

Section: Introductionmentioning

confidence: 99%

Monoliths with immobilized zirconium ions for selective enrichment of phosphopeptides

Wang

Duan

et al. 2011

J of Separation Science

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To meet the demands of protein phosphorylation study, immobilized zirconium ion affinity chromatography (Zr 41 -IMAC) monolith was prepared by combining UV-initiated polymerization of monolithic support and subsequent photografting in both capillary columns and microchannels. Hydrophilic poly(2-hydroxyethyl methacrylate (HEMA)-coethylene dimethacrylate (EDMA)) monolithic support was prepared under UV irradiation at the wavelength of 365 nm with monomer HEMA, crosslinker EDMA and 2,2-dimethoxy-2-phenylacetophenone as photoinitiator in 1-decanol solution, which provides good biocompatibility and permeability for biomolecule analysis. To introduce chelating ligands, such as phosphate groups, on the pore surface of monolith for metal ion immobilization, photografting of ethylene glycol methacrylate phosphate with benzophenone as the photoinitiator was performed at 254 nm for 300 s. The grafting process and metal ion immobilization can be monitored by measuring the electroosmotic flow produced by the modified monolith, providing a quantitative evaluation of post-modification. This new method for the preparation of Zr 41 -IMAC monolith simplifies the optimization of monolith preparation and avoids the time-consuming chemical modification process. Additionally, advantages include facile preparation in microdevices, easy regenerability and good reproducibility. After optimization, the microchip-based Zr 41 -IMAC monolith was used for phosphopeptide analysis and showed good selectivity in phosphopeptide enrichment with matrix-assisted laser desorption ionization mass spectrometry detection. IntroductionIn recent years, protein phosphorylation has gained much attention because of its significant roles in cellular signal transduction processes [1,2]. However, the amount of phosphorylated proteins in eukaryotic cells often exists in substoichiometry level, which makes the identification of phosphorylation sites challenging [3]. To date, mass spectrometry (MS) analysis has become an effective and commonly used method for characterization of phosphoproteins [4]. To reduce the interference of non-phosphopeptides, selective enrichment strategies, such as immobilized metal ion affinity chromatography (IMAC) [5][6][7], metal oxide affinity chromatography (MOAC) [8,9], and ion exchange chromatography [10][11][12][13], are necessary before MS analysis.Recently, chip-based system has been introduced as a promising platform for phosphopeptide analysis, due to the benefits of low sample amount, high throughput, and easy integration [14]. Several microfluidic devices have been developed by integrating phosphopeptide enrichment with other functions, such as protein alkylation and reduction [15], protein digestion [16], peptide separation and on-line interface for MS instrument [17][18][19][20], which have shown great potentials in the field of phosphoproteome research. However, in these microchip devices, phosphopeptide enrichment components are usually fabricated by packing functionalized particles, such as TiO 2 or IMAC beads, into m...

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Impact of Conduit Geometry on the Performance of Typical Particulate Microchip Packings

Cited by 32 publications

References 43 publications

Transient and asymptotic dispersion in confined sphere packings with cylindrical and non-cylindrical conduit geometries

Transient and asymptotic dispersion in confined sphere packings with cylindrical and non-cylindrical conduit geometries

Bed morphological features associated with an optimal slurry concentration for reproducible preparation of efficient capillary ultrahigh pressure liquid chromatography columns

Monoliths with immobilized zirconium ions for selective enrichment of phosphopeptides

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