Principles of gradient elution

Snyder, Lloyd R.

doi:10.1016/0009-5907(65)80002-3

Cited by 107 publications

(13 citation statements)

References 119 publications

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“…Snyder’s work has been mentioned [17, 18]. Later, the Poppe group combined the on-column focusing and the step-gradient-induced compression in the context of a precolumn trapping column/backflush for analytical work [19, 20].…”

Section: Introductionmentioning

confidence: 99%

Quantitative evaluation of models for solvent-based, on-column focusing in liquid chromatography

Groskreutz

Weber

2015

Journal of Chromatography A

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On-column focusing or preconcentration is a well-known approach to increase concentration sensitivity by generating transient conditions during the injection that result in high solute retention. Preconcentration results from two phenomena: 1) solutes are retained as they enter the column. Their velocities are k′-dependent and lower than the mobile phase velocity and 2) zones are compressed due to the step-gradient resulting from the higher elution strength mobile phase passing through the solute zones. Several workers have derived the result that the ratio of the eluted zone width (in time) to the injected time width is the ratio k2/k1 where k1 is the retention factor of a solute in the sample solvent and k2 is the retention factor in the mobile phase (isocratic). Mills et al. proposed a different factor. To date, neither of the models has been adequately tested. The goal of this work was to evaluate quantitatively these two models. We used n-alkyl esters of p-hydroxybenzoic acid (parabens) as solutes. By making large injections to create obvious volume overload, we could measure accurately the ratio of widths (eluted/injected) over a range of values of k1 and k2. The Mills et al. model does not fit the data. The data are in general agreement with the factor k2/k1, but focusing is about 10% better than the prediction. We attribute the extra focusing to the fact that the second, compression, phenomenon provides a narrower zone than that expected for the passage of a step gradient through the zone.

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Section: Introductionmentioning

confidence: 99%

Quantitative evaluation of models for solvent-based, on-column focusing in liquid chromatography

Groskreutz

Weber

2015

Journal of Chromatography A

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“…The general elution problem (1) in HPLC is usually solved by application of gradient elution (1)(2)(3)(4)(5)41,42). The technique can also be applied in TLC (3,(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(21)(22)(23)(24)(28)(29)(30)(31).…”

Section: B Mobile-phase Gradientmentioning

confidence: 98%

“…1 (neglecting the second term) as Then the fractional distance r a>1) and r a -, 2 values obtained under step wise gradient conditions. After introduction of R f values of the sample components obtained for several isocratic runs, the microcomputer calculates R f values for any gradient program and displays the paths of migration of the spots through the concentration zones.…”

mentioning

confidence: 99%

Gradient Development in Thin-Layer Chromatography

Gotkiewicz¹

2003

Handbook of Thin-Layer Chromatography

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“…The first theoretical discussion of the possibilities of peak refocusing was made by Snyder and Poppe [21,22], who calculated that the enhancement of the peak would simply be given by the factor kload/kelut, wherein kload and kelut respectively are the retention factor of the analyte in the loading and the elution eluent. This was later verified by Hartwhick and our own group [18][19]23].…”

Section: Introductionmentioning

confidence: 99%

Peak sharpening limits of solvent-assisted post-column refocusing to enhance detection limits in liquid chromatography

Pepermans

Vos

Eeltink

et al. 2019

Journal of Chromatography A

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Highlights Limits of post-column peak refocusing are established across broad parameter space  The need for a sufficiently steep remobilization gradient has been demonstrated  Achieving the theoretical upper limit requires trapping sufficiently large volumes  Trapping columns should be sufficiently narrow to limit dispersion Abstract We report on a numerical and experimental study of the limits of peak refocusing and concentration enhancement that can be obtained with solvent front-assisted peak remobilization in a trap column receiving peaks eluting from a preceding analytical column. It is shown that the upper limit of peak refocusing can best be pursued by injecting a sufficiently large volume in a sufficiently narrow capillary and elute it with a ballistic gradient with a sufficiently steep gradient. Equations offering a quantitative description of these rules have been derived and verified experimentally. For the latter purpose, peak volumes of the order of 0.5 to 2 L were refocused in a dedicated set-up capable of trapping L-sized peaks in a 75 m capillary and remobilized using a nano-LC pump propelling an acetonitrile/isopropyl alcohol mixture with a viscosity matching that of the trapping solvent. Injecting 2L peaks, a peak refocusing factor of 17.3 could be achieved.

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Principles of gradient elution

Cited by 107 publications

References 119 publications

Quantitative evaluation of models for solvent-based, on-column focusing in liquid chromatography

Quantitative evaluation of models for solvent-based, on-column focusing in liquid chromatography

Gradient Development in Thin-Layer Chromatography

Peak sharpening limits of solvent-assisted post-column refocusing to enhance detection limits in liquid chromatography

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