Temperature effects in capillary electrophoresis 2: Some theoretical calculations and predictions

Knox, John H.; McCormack, K. A.

doi:10.1007/bf02290339

Cited by 76 publications

(50 citation statements)

References 3 publications

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“…Joule heating and determination of temperatures in CE and CEC has been discussed by Knox and McCormack [17,18], Petersen et al [19], and in Rathore's 2004 review article [20]. Contributions most relevant to this work and recent developments are discussed below.…”

Section: General Aspectsmentioning

confidence: 96%

Internal electrolyte temperatures for polymer and fused-silica capillaries used in capillary electrophoresis

et al. 2005

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Polymers are important as materials for manufacturing microfluidic devices for electrodriven separations, in which Joule heating is an unavoidable phenomenon. Heating effects were investigated in polymer capillaries using a CE setup. This study is the first step toward the longer-term objective of the study of heating effects occurring in polymeric microfluidic devices. The thermal conductivity of polymers is much smaller than that of fused silica (FS), resulting in less efficient dissipation of heat in polymeric capillaries. This study used conductance measurements as a temperature probe to determine the mean electrolyte temperatures in CE capillaries of different materials. Values for mean electrolyte temperatures in capillaries made of New Generation FluoroPolymer (NGFP), poly-(methylmethacrylate) (PMMA), and poly(ether ether ketone) (PEEK) capillaries were compared with those obtained for FS capillaries. Extrapolation of plots of conductance versus power per unit length (P/L) to zero power was used to obtain conductance values free of Joule heating effects. The ratio of the measured conductance values at different power levels to the conductance at zero power was used to determine the mean temperature of the electrolyte. For each type of capillary material, it was found that the average increase in the mean temperature of the electrolyte (DeltaT(Mean)) was directly proportional to P/L and inversely proportional to the thermal conductivity (lambda) of the capillary material. At 7.5 W/m, values for DeltaT(Mean) for NGFP, PMMA, and PEEK were determined to be 36.6, 33.8, and 30.7 degrees C, respectively. Under identical conditions, DeltaT(Mean) for FS capillaries was 20.4 degrees C.

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Section: General Aspectsmentioning

confidence: 96%

Internal electrolyte temperatures for polymer and fused-silica capillaries used in capillary electrophoresis

et al. 2005

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“…Joule heating will thus generate a radial temperature profile across the channel. It was established earlier that this radial temperature profile can be described by a parabolic function [19,[28][29][30]. For a conventional fused-silica capillary with an external polyimide coating this temperature profile is given by…”

Section: Radial Temperature Profiles In the Devicesmentioning

confidence: 99%

Effect of Joule heating on efficiency and performance for microchip‐based and capillary‐based electrophoretic separation systems: A closer look

et al. 2004

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An attempt is made to revisit the main theoretical considerations concerning temperature effects ("Joule heating") in electro-driven separation systems, in particular lab-on-a-chip systems. Measurements of efficiencies in microfabricated devices under different Joule heating conditions are evaluated and compared to both theoretical models and measurements performed on conventional capillary systems. The widely accepted notion that planar microdevices are less susceptible to Joule heating effects is largely confirmed. The heat dissipation from a nonthermostatically controlled glass microdevice was found to be comparable to that from a liquid-cooled-fused silica capillary. Using typically dimensioned glass and glass/silicon microdevices, the experimental results indicate that 5-10 times higher electric field strengths can be applied than on conventional capillaries, before detrimental effects on the separation efficiency occur. The main influence of Joule heating on efficiency is via the establishment of a radial temperature profile across the lumen of the capillary or channel. An overall temperature increase of the buffer solution has only little influence on the quality of the separation. Still, active temperature control (cooling, thermostatting) can help prevent boiling of the buffer and increase the reproducibility of the results.

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“…25 nL) was injected by pressure (1000 mbar-s) and electrophoresis was performed after a 1 min voltage ramp. This voltage ramp improves repeatability, because it ensures that there is no loss of sample after injection due to excessive Joule heating [38]. Detection was performed by using a diode-array detector scanning the wavelengths from 190 to 600 nm; the pherograms were monitored at 200 nm (10 nm band width) and a reference signal at 350 nm (100 nm band width).…”

Section: Instrumentationmentioning

confidence: 99%

Central composite design in the chiral analysis of amphetamines by capillary electrophoresis

et al. 1997

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We have studied a central composite design for the chiral separation of amphetamines using capillary electrophoresis. Five variables, i.e., buffer concentration, pH, chiral selector concentration, temperature, and applied voltage, were investigated. Enantiomeric resolutions as well as analysis time and generated power were established as responses for each experiment. A model of each response was obtained by multiple regression of a quadratic-degree mathematical expression. From the models, we determined the most favorable conditions for the chiral separation by optimizing the resolution and setting the other responses at threshold values. Results were compared with a previous study in which a systematic investigation of the operating parameters was carried out. In order to visualize the robustness of the method, response surfaces were drawn for the significant variables. We have concluded that experimental designs offer a rapid means of optimizing several variables and provide an efficient test for the robustness of the analytical method.

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Temperature effects in capillary electrophoresis 2: Some theoretical calculations and predictions

Cited by 76 publications

References 3 publications

Internal electrolyte temperatures for polymer and fused-silica capillaries used in capillary electrophoresis

Internal electrolyte temperatures for polymer and fused-silica capillaries used in capillary electrophoresis

Effect of Joule heating on efficiency and performance for microchip‐based and capillary‐based electrophoretic separation systems: A closer look

Central composite design in the chiral analysis of amphetamines by capillary electrophoresis

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