Analysis of chromatography by plate theory

Lee, Wen‐Chien; Tsai, Guo-Jane; Tsao, George T.

doi:10.1016/0956-9618(93)80018-m

Cited by 18 publications

(12 citation statements)

References 100 publications

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“…Conventionally, column properties may be described in terms of plate theory, which describes the peak shape and resolution of chromatographic systems [23,34]. A narrow peak is desirable in chromatography as it indicates good resolution and high sensitivity [5,14,18]. Thus, the length of the column, L, is divided by the number of theoretical plates of the column, which gives the height equivalent to the theoretical plate (HETP) [23,57] according to Eq.…”

Section: The Van Deemter Equationmentioning

confidence: 99%

“…Recent developments in chromatography include analysis of chiral compounds [2], high-speed analysis [3][4][5], microanalysis [6][7][8], nano analysis [9] and lab-on-a chip [10]. The optimization and understanding of chromatographic systems rely on two theories or combinations thereof: adsorption theory [11,12] and plate theory [13,14]. The retention and separation of chemical species is understood in terms of adsorption and partitioning [13].…”

Section: Introductionmentioning

confidence: 99%

“…Peak broadening [25] originates from several contributions comprising longitudinal diffusion, eddy diffusion, mobile-phase mass transfer, stagnant-mobile-phase mass transfer and stationary-phase mass transfer [26]. The efficacy of peak separation and retention depends on the column length, temperature [27], particle size of the stationary phase, porosity of the column material [14,28], column packing [29,30], flow rate [7], diffusion rate and, to a large extent, composition of the mobile phase [31]. In high-performance liquid chromatography (HPLC), changing the solvent composition of the mobile phase corresponds to an adjustment of the hydrophobic and hydrophilic interactions among the solute, mobile phase and stationary phase [31,32].…”

Section: Introductionmentioning

confidence: 99%

“…However, turbulent flow may be observed at Reynolds numbers much lower than 2500, even as low as 1-10, when retention is induced by chromatographic columns [34]. Most chromatographic theories predict a Gaussian-shaped distribution of concentrations along the length of the pipe [13,14], and the corresponding full width at half maximum (FWHM) increases as a function of time when the segment moves downstream. The optimum conditions of peak shape with respect to chromatographic separation are described by the Van Deemter equation [23], which is widely used for purposes of optimization [35].…”

Section: Introductionmentioning

confidence: 99%

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Signal convolution indicates chromatographic pulse flow and open-end flow

2019

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Only slices are measured of very long segments of solute molecules that are injected into columns in chromatographic systems. Since the concentration of solute molecules changes during elution as a function of time, the observed signal should be reconstructed for a comparison of experimental results with theory. The influence of response time on the observed signal in high-performance liquid chromatography experiments was investigated in detail using a C-18 column for the measurement of caffeine in pure methanol as eluent. The response function influenced the observed signal by converting the square signal of pulse flow into a chromatographic peak. At faster linear flow rates (LFRs), the response function influenced the observed shape of the chromatographic peak, whereas diffusion dominated at slow LFRs. By convolution of the square signal with the response function, it was possible to predict the shape of the observed signal and chromatographic parameters and to provide an alternative explanation to the van Deemter equation. By using the shape of a known response function and modelling the new theory to data, it was proposed that the injected solute molecules were eluted over long distances through the chromatographic column, distances that are much longer than the physical length of the system.

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Section: The Van Deemter Equationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Signal convolution indicates chromatographic pulse flow and open-end flow

2019

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“…An understanding of the mechanisms underlying band broadening permits improved columnar design as well a predicting what conditions must be contrived in order to minimise the height equivalent to a theoretical plate, H, for any given column. Several relationships between H and the linear flow velocity, u, have been proposed [1]. Work of Van Deemter et al [2] led to a model describing the relationship between H and u which is widely cited in the literature.…”

Section: Introductionmentioning

confidence: 98%

Comparison of equations describing band broadening in high-performance liquid chromatography

Kirkup

Foot

Mulholland

2004

Journal of Chromatography A

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Evaluation of the van Deemter equation in terms of open‐ended flow to chromatography

Andersen

Mukami

Maina

2020

J of Separation Science

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Plate theory and adsorption theory are the main tools available for understanding chromatographic experiments. Both theories predict a Gaussian distribution of solute molecules within the tubular system. However, Gaussian concentration distributions are observed predominantly at slow linear flow rates, while asymmetric concentration distributions are observed at the linear flow rates most used in chromatography. Allegedly, this asymmetry originates from an inhomogeneous distribution of grain sizes in the column and column overload. However, it is an experimental fact that the distribution of chemicals within an injected volume of solute changes as a function of time, while the response is measured simultaneously. Accordingly, the obtained signal cannot be compared to the theory before some type of time‐based deconvolution of the data has been performed. Adjustments to high‐performance liquid chromatography data were thus proposed through empirical equations that describe the relevant time values, peak height, peak area, and parameters of the van Deemter equation. It was proposed that the transfer of solute from the front to the rear part of the pulse during laminar open‐ended flow occurs at rate that depends on the linear flow rate, and to a lesser extent, on properties of the response function.

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Analysis of chromatography by plate theory

Cited by 18 publications

References 100 publications

Signal convolution indicates chromatographic pulse flow and open-end flow

Signal convolution indicates chromatographic pulse flow and open-end flow

Comparison of equations describing band broadening in high-performance liquid chromatography

Evaluation of the van Deemter equation in terms of open‐ended flow to chromatography

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