A generic approach to post-column refocusing in liquid chromatography

Vos, Jelle De; Desmet, Gert; Eeltink, Sebastiaan

doi:10.1016/j.chroma.2014.07.072

Cited by 26 publications

(17 citation statements)

References 25 publications

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“…Such kind of band expansion has been observed experimentally also, which spoils the separation process. 39 The simulation results obtained from this model are in a good qualitative agreement with the experiments where strong solvent and viscous instability play an independent role, 15,29 as well as with the combined effects of both VF and solvent strength (recently observed in liquid chromatography experiments by De Vos et al 32 ). Similarly, for soil contamination, fingering will be a major problem when accompanied with the solvent strength due to enhancement of spreading of pollutants.…”

Section: Discussionsupporting

confidence: 79%

“…Moreover, it can be clearly seen in experiment of water, acetontrile (ACN), and isopropanol (IPA) system, symmetrical peak profiles were observed for lower solvent strength that was achieved by considering low ACN percentage (18%-36%) and greatly distorted peaks with severe fronting were observed with increasing solvent strength (using remobilization solvents of 54%-63% ACN) (see Fig. 5 of De Vos et al 32 ).…”

Section: Effects Of Solvent Strength Parameter S *mentioning

confidence: 87%

“…31 However, when there is a viscosity contrast between the sample and the displaying fluid, VF starts playing simultaneously with the solvent strength effect. Recently, it has been observed experimentally by De Vos et al 32 that the presence of a strong solvent affects the solute propagation depending on fingering at frontal or the rear interface of the sample. The theoretical study, with the viscosity of the sample plug higher than the displacing fluid, shows that the VF occurring at the rear interface of the sample along with the solvent strength counter-act with each other.…”

Section: Introductionmentioning

confidence: 97%

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Fingering dynamics on the adsorbed solute with influence of less viscous and strong sample solvent

Rana

Mishra

2014

The Journal of Chemical Physics

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Viscous fingering is a hydrodynamic instability that sets in when a low viscous fluid displaces a high viscous fluid and creates complex patterns in porous media flows. Fundamental facets of the displacement process, such as the solute concentration distribution, spreading length, and the solute mixing, depend strongly on the type of pattern created by the unstable interface of the underlying fluids. In the present study, the frontal interface of the sample shows viscous fingering and the strong solvent causes the retention of the solute to depend on the solvent concentration. This work presents a computational investigation to explore the effect of the underlying physico-chemical phenomena, (i.e., the combined effects of solvent strength, retention, and viscous fingering) on the dynamics of the adsorbed solute. A linear adsorption isotherm has been assumed between the mobile and stationary phases of the solute. We carried out the numerical simulations by considering a rectangular Hele-Shaw cell as an analog to 2D-porous media containing a three component system (displacing fluid, sample solvent, solute) to map out the evolution of the solute concentration. We observed that viscous fingering at the frontal interface of the strong sample solvent intensifies the band broadening of the solute zone. Also notable increase in the spreading dynamics of the solute has been observed for less viscous and strong sample solvent as compared to the high viscous sample slices or in the pure dispersive case. On the contrary, the solute gets intensively mixed at early times for more viscous sample in comparison to less viscous one. The results of the simulations are in qualitative agreement with the behavior observed in the liquid chromatography column experiments.

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Section: Discussionsupporting

confidence: 79%

Section: Effects Of Solvent Strength Parameter S *mentioning

confidence: 87%

Section: Introductionmentioning

confidence: 97%

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Fingering dynamics on the adsorbed solute with influence of less viscous and strong sample solvent

Rana

Mishra

2014

The Journal of Chemical Physics

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“…The latter recommendation can result in detrimental viscous fingering effects, which should be addressed. The generic post‐column refocusing approach, and its different parameters, were studied under isocratic and gradient reversed‐phase conditions amounting for signal enhancement factors of well over one order of magnitude 128,129 . Figure 3B shows the result of post‐column refocusing performed on an antibiotics sample in gradient elution mode, enhancing the detection sensitivity with a factor of 14.…”

Section: Multi‐dimensional Lc Workflowsmentioning

confidence: 99%

Advances in ultra‐high‐pressure and multi‐dimensional liquid chromatography instrumentation and workflows

Vos

Stoll

Buckenmaier

et al. 2021

Analytical Science Advances

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The present contribution discusses recent advances in ultra‐high‐pressure liquid chromatography (UHPLC) and multi‐dimensional liquid chromatography (MDLC) technology. First, new developments in UHPLC column technology and system design are highlighted. The latter includes a description of a novel injector concept enabling method speed‐up, emerging detectors, and instrument diagnostics approaches. Next, online MDLC workflows are reviewed and advances in modulation technology are highlighted. Finally, key applications published in 2020 are reviewed.

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“…Such on-column focusing may lack the ability to take advantage of solute-specific focusing approaches such as SPE, but it is very convenient, performed on a single column and widely applicable. On-column focusing at the column head focuses all analytes in the mixture in contrast to post-column trapping and remobilization approaches that enhance signal for one or two specific solutes in the mixture [30–33]. One process that would be difficult to accomplish using online solvent-based focusing is to amplify the effect by carrying out the focusing process twice, in series, on the same column.…”

Section: Introductionmentioning

confidence: 99%

Temperature-assisted solute focusing with sequential trap/release zones in isocratic and gradient capillary liquid chromatography: Simulation and experiment

Groskreutz

Weber

2016

Journal of Chromatography A

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In this work we characterize the development of a method to enhance temperature-assisted on-column solute focusing (TASF) called two-stage TASF. A new instrument was built to implement two-stage TASF consisting of a linear array of three independent, electronically controlled Peltier devices (thermoelectric coolers, TECs). Samples are loaded onto the chromatographic column with the first two TECs, TEC A and TEC B, cold. In the two-stage TASF approach TECs A and B are cooled during injection. TEC A is heated following sample loading. At some time following TEC A’s temperature rise, TEC B’s temperature is increased from the focusing temperature to a temperature matching that of TEC A. Injection bands are focused twice on-column, first on the initial TEC, e.g. single-stage TASF, then refocused on the second, cold TEC. Our goal is to understand the two-stage TASF approach in detail. We have developed a simple yet powerful digital simulation procedure to model the effect of changing temperature in the two focusing zones on retention, band shape and band spreading. The simulation can predict experimental chromatograms resulting from spatial and temporal temperature programs in combination with isocratic and solvent gradient elution. To assess the two-stage TASF method and the accuracy of the simulation well characterized solutes are needed. Thus, retention factors were measured at six temperatures (25–75 °C) at each of twelve mobile phases compositions (0.05–0.60 acetonitrile/water) for homologs of n-alkyl hydroxylbenzoate esters and n-alkyl p-hydroxyphenones. Simulations accurately reflect experimental results in showing that the two-stage approach improves separation quality. For example, two-stage TASF increased sensitivity for a low retention solute by a factor of 2.2 relative to single-stage TASF and 8.8 relative to isothermal conditions using isocratic elution. Gradient elution results for two-stage TASF were more encouraging. Application of two-stage TASF increased peak height for the least retained solute in the test mixture by a factor of 3.2 relative to single-stage TASF and 22.3 compared to isothermal conditions for an injection four-times the column volume. TASF improved resolution and increased peak capacity; for a 12-minute separation peak capacity increased from 75 under isothermal conditions to 146 using single-stage TASF, and 185 for two-stage TASF.

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A generic approach to post-column refocusing in liquid chromatography

Cited by 26 publications

References 25 publications

Fingering dynamics on the adsorbed solute with influence of less viscous and strong sample solvent

Fingering dynamics on the adsorbed solute with influence of less viscous and strong sample solvent

Advances in ultra‐high‐pressure and multi‐dimensional liquid chromatography instrumentation and workflows

Temperature-assisted solute focusing with sequential trap/release zones in isocratic and gradient capillary liquid chromatography: Simulation and experiment

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