Separation of homologues of organic compounds using the gradient of the eluent flow rate on a monolithic porous column

Nesterenko, Pavel N.; Rybalko, M. A.

doi:10.1007/s10809-005-0097-7

Cited by 13 publications

(5 citation statements)

References 14 publications

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“…[8][9][10][11] As another type of gradient method for LC, a gradient in flow velocity was recently reported using a monolithic column, wherein the elution of highly retained analytes was gradually accelerated through an increase in the flow rate. 12,13 On the other hand, in the case of CEC, a gradient in the applied voltage was reported to control the electroosmotic flow velocity and the electrophoretic migration of an ionized analyte. 14,15 A gradient in the pressurized flow velocity identically varies the migration velocity of all the analytes in the mobile phase; however, the applied-voltage gradient can individually vary the electrophoretic velocity of each analyte, owing to the difference in their electrophoretic mobilities.…”

Section: Introductionmentioning

confidence: 99%

Dual-Gradient Capillary Electrochromatography by Varying the Mobile Phase Composition and Applied Voltage

2008

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Dual-gradient capillary electrochromatography (DG-CEC) was developed to provide superior performance with regard to the separation of ionized analytes; in this method, both the eluent composition and the applied voltage are varied during the separation procedure. As for the gradient in the eluent composition, a shift in the pH is employed to control not only the electrophoretic mobility, but also the retention factor of the analytes. The dual-gradient method was shown to be effective in increasing the resolution and reducing the chromatographic period of ionized analytes. Fourteen kinds of o-phthalaldehyde labeled amino acids were separated within 8 min using DG-CEC with multistage enlargement in the applied voltage. The separation efficiency increased particularly for highly retained amino acids in the dual-gradient, as compared to those in the ordinary single-gradient for the eluent.

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Section: Introductionmentioning

confidence: 99%

Dual-Gradient Capillary Electrochromatography by Varying the Mobile Phase Composition and Applied Voltage

2008

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“…If there is a late eluting peak in your chromatogram, monolithic columns offer you the possibility to easily solve this by applying an elution type called flow programming which is usually not helpful with conventional particulate columns. Flow rate programming has been previously used in microcolumn HPLC [40,54,[66][67][68][69][70][71][72]. Flow programming is used to offer a gradual increase in elution power by increasing mobile phase flow rate throughout the chromatographic run.…”

Section: High Flow Rate Versus Flow Programmingmentioning

confidence: 99%

Monolithic Silica for Fast HPLC: Current Success and Promising Future

Deeb

2011

Chromatographia

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As an approach for fast HPLC, monolithic silica has proven to be highly effective. It is especially successful for routinely obtaining fast isocratic HPLC analyses of small drug molecules. The low cost of monolithic compared with other approaches, such as UPLC, makes it more convenient for everyday application. It is also the more developed and widely applied technique compared with superficially porous particles. It offers the possibility for gaining high plate numbers through column coupling, but not at the expense of run time if a proper flow program is subsequently applied. Good precision and batch reproducibility are now achieved with commercially available monolithic silica columns. The application of monolithic silica columns is already well developed in various fields. It invades the field of bio-analysis and proteomics. Hundreds of analytical methods have already been successfully transferred to or developed on monolithic silica columns. An updated strategy based on Snyder's method for rapid method development using monolithic column has been provided. However, more is still to be expected from monolithic silica in term of chemistry variation, application, and instrument compatibility. The future of monolithic silica is promising when considering the high demand for fast chromatographic analysis.

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“…It can be seen from Table 1 that the C values describing the mass transfer resistance and the contribution of convection are two to three times lower for the monolithic column than for the packed column [9]. According to the Rodrigues theory [10], this indicates that the sorptiondesorption rate on a monolithic column is much higher and is approximately equal for homologues.…”

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confidence: 93%

The Use of Ultrashort Monolithic Porous Columns and an Eluent Flow Gradient for Chromatographic Separation of Polyaromatic Hydrocarbons

Nesterenko

Rybalko

2005

Dokl Chem

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An important task of state-of-the-art high performance liquid chromatography (HPLC) is to decrease the time of analysis. There exist several approaches to solving this task. The first one implies the use of short (3 − 5 cm long) columns packed with particles 1.5-3 µ m in diameter [1]. These tiny particles ensure an effective mass transfer and rather high column efficiency. Complete separation of five inorganic anions requires 2 min at a flow rate of 1 mL/min. However, the high pressure at the column inlet precludes the possibility of increasing the eluent flow rate and thus of reducing additionally the time of analysis. For separation at higher flow rates, it is necessary to raise the column temperature. The pressure at the column inlet is more than 10 MPa at a flow rate of 2.5 mL/min and a temperature of 45 ° ë .To induce chromatographic peaks in the chromatogram to move toward one another and, hence, to reduce the time of analysis, a concentration gradient is created for the mobile phase component having a higher elution ability. The concentration gradient is formed by means of a special system of mixing eluents and eluent degassing, which substantially complicates the design and increases the cost of a chromatograph.An important alternative is an eluent flow gradient, which allows one to optimize the separation using one pump with flow rate programming. An advantage of a flow gradient over a concentration gradient is elimination of the need to equilibrate the chromatographic system after each separation [2]. Unfortunately, for chromatographic columns packed with microspherical particles, the use of a flow gradient is restricted by the high flow resistance, which markedly narrows the range of variation of flow rates for these columns.A possible solution of the problem is the use of monolithic porous columns. These columns have two types of pores, namely, through (transport) pores that ensure a low pressure at the column inlet and mesopores that form a developed surface with a large area and ensure a high load capacity [3]. This structure allows one to reduce the time of chromatographic analysis five-to sixfold with respect to the classical columns packed with microspherical particles. Indeed, a 10-cmlong monolithic porous column 4.6 mm in diameter allows the separation of five β -blockers in 1 min at an eluent flow rate of 9 mL/min, the resolution of the column being retained at a level as high as that at a flow rate of 1 mL/min [2]. Using a monolithic porous column, one can further reduce the time of chromatographic analysis by decreasing the length of the column and by using simultaneously two gradient elution modes, i.e., both the concentration and the flow gradients [4].Analytical practice is often faced with tasks for which the efficiency of a conventional chromatographic column, 5-10 cm long, is excessive. The advent of

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Separation of homologues of organic compounds using the gradient of the eluent flow rate on a monolithic porous column

Cited by 13 publications

References 14 publications

Dual-Gradient Capillary Electrochromatography by Varying the Mobile Phase Composition and Applied Voltage

Dual-Gradient Capillary Electrochromatography by Varying the Mobile Phase Composition and Applied Voltage

Monolithic Silica for Fast HPLC: Current Success and Promising Future

The Use of Ultrashort Monolithic Porous Columns and an Eluent Flow Gradient for Chromatographic Separation of Polyaromatic Hydrocarbons

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