Sensitivity enhancement in capillary electrochromatography by on-column preconcentration

Hilhorst, M.J; Somsen, G.W; Jong, G.J. de

doi:10.1007/bf02491569

Cited by 13 publications

(9 citation statements)

References 31 publications

(14 reference statements)

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“…Hartwick, and subsequently the Desmet group found the same relationship for post-column peak trapping/concentration and elution [21–23]. The same relationship was found for preconcentration in CEC [24]. …”

Section: Introductionmentioning

confidence: 77%

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: 77%

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 focusing effects of on-line concentration in CEC with both conventional particulate packed columns and monolithic columns involve stepwise gradient elution [6][7][8], the preparation of a sample in a noneluting solvent, or/ and the introduction a water plug after injection [9,10]. Recently, we proposed a CEC on-line concentration technique with a 3 mm octadecyl silica (ODS)-packed column.…”

Section: Introductionmentioning

confidence: 99%

On‐line concentration of neutral and charged species in capillary electrochromatography with a methacrylate‐based monolithic stationary phase

Ping

Zhang

et al. 2004

Electrophoresis

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On-line concentration of neutral and charged species in capillary electrochromatography with a methacrylate-based monolithic stationary phase A method involving self-concentration, on-column enrichment and field-amplified sample stacking for on-line concentration in capillary electrochromatography with a polymer monolithic column is presented. Since monolithic columns eliminate the frit fabrication and the problems associated with frits, the experimental conditions could be more flexibly adjusted to obtain higher concentration factor in comparison with conventional particulate packed columns. With self-concentration effect, the detection sensitivity of benzene and hexylbenzene is improved by a factor of 4 and 8, respectively. With on-column enrichment and ultralong injection, improvement as high as 22 000 times in detection sensitivity of benzoin is achieved. Furthermore, a combination of the three above-mentioned methods yields up to a 24 000-fold improvement in detection sensitivity for caffeine, a charged compound. Parameters affecting the efficiency of on-line concentration are investigated systematically. In addition, equations describing on-line concentration process are deduced.

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“…Hilhorst and co-workers [87] analyzed two test mixtures containing pharmaceutically relevant steroids (desogestrel and analogues and tibolon and analogues) on a Hypersil ODS column. On-column preconcentration was applied to enhance sensitivity.…”

Section: Steroidsmentioning

confidence: 99%

Recent applications of capillary electrochromatography

et al. 2001

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A review is presented of the most important recent applications of capillary electrochromatography (CEC) for the analysis of acidic, basic, and neutral compounds, of biomolecules, environmental substances, natural products, pharmaceuticals, and chiral compounds. Packed-column CEC (packed-CEC), open-tubular (OT-CEC), as well as pressure-assisted CEC (pseudo-CEC) are hereby considered. Papers published between July 1999 and April 2001 were taken into account. Applications before July 1999 have been reviewed in Electrophoresis 1999, 20, 3027-3065.

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Sensitivity enhancement in capillary electrochromatography by on-column preconcentration

Cited by 13 publications

References 31 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

On‐line concentration of neutral and charged species in capillary electrochromatography with a methacrylate‐based monolithic stationary phase

Recent applications of capillary electrochromatography

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