Spatially resolved temperature measurements in electrophoresis capillaries by Raman thermometry

Davis, Kevin L.; Liu, Kei Lee K.; Lanan, Maureen; Morris, Michael D.

doi:10.1021/ac00051a018

Cited by 54 publications

(43 citation statements)

References 27 publications

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“…For these purposes thermochromic solutions [14], Raman spectroscopy [15,16], or NMR thermometry [17] have been utilized. In most cases a good accordance between theory and experiments was observed, though some discrepancies remained.…”

Section: Introductionmentioning

confidence: 99%

Influence of solvent on temperature and thermal peak broadening in capillary zone electrophoresis

et al. 2003

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The present paper deals with the role of the solvent on thermal peak broadening. One main solvent property that determines the magnitude of the temperature gradient due to the generation of Joule heat in capillary zone electrophoresis is the thermal conductivity. As organic solvents have lower thermal conductivity than water (methanol and acetonitrile, e.g., nearly by a factor of 3) it can be hypothesized that the temperature gradient inside the capillary is more pronounced in organic solvents compared to an aqueous solution. On the other hand, the temperature dependence of the ion mobility (which is responsible for the velocity profile and thus for thermal peak broadening) is smaller in organic solvents. To get insight into the thermal effect of the solvent, first the temperature of a solution in a cylindrical tube was calculated utilizing the heat balance equation. It was shown that the two theoretical models most common in the literature (based on the analytical solution or on an assumption of the parabolic temperature profile in the tube, respectively) give the same results. The latter model was chosen for the further calculations, adding a quadratic term to express the electric conductivity as a function of the temperature. The temperature at the inner capillary wall and center as function of the capillary dimensions and the electric power was computed for electrolytes with a given conductivity at 25.0 degrees C with water, methanol, and acetonitrile as solvents. Capillary cooling systems used were circulating liquid cooling, enforced air-cooling, and natural convection in still air. The mean temperature (averaged over the cross section) resulting from Joule heating was compared with experimentally determined temperatures established upon application of an electric field; the latter temperature was derived from the measurement of the electric conductance of the background electrolyte solution and its (measured) temperature dependence. All investigations were carried out with solutions of the same initial electric conductivity (about 0.5 S.m(-1) at 25.0 degrees C). Agreement is found for natural convection conditions, and the deviation between theoretical and experimental results for the forced air and circulated liquid cooling systems can be related to the poorly defined thermal conditions of the capillaries in commercial instrumentation (with a part in a thermostated cassette and a part outside). For given conditions the temperature gradients in the organic solvents exceed largely those in water, independent of the type of cooling. As a consequence, the thermal plate height is significantly larger in organic solvents, at least under conditions where the deviation from the Nernst-Einstein limiting case is not too high. However, even for the maximum applicable field strengths the thermal plate height contributions are negligible compared to longitudinal diffusion in all solvents.

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Section: Introductionmentioning

confidence: 99%

Influence of solvent on temperature and thermal peak broadening in capillary zone electrophoresis

et al. 2003

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“…Experimental methods of determining electrolyte temperatures include the use of external thermocouples [20,56,57], NMR thermometry [58,59] Raman spectroscopy [60,61], temperature-dependent absorbance [62], conductivity [10,13,32,63,64], m EOF [13,32] m ep [13], refractive index [65] and fluorescence [46,66]. All have been dealt with comprehensively in Rathore's review for the decade preceding 2004 [53].…”

Section: Experimental Methods Of Determining Temperaturementioning

confidence: 99%

Joule heating effects and the experimental determination of temperature during CE

Evenhuis

Haddad

2009

Electrophoresis

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Joule heating is ubiquitous in electrokinetic separations. This review is in two major parts. The first part documents the effects of Joule heating on the physical properties of the electrolyte and efficiency of separations and the second part focuses on advances in the determination of electrolyte temperatures that have been described in the literature over the past 5 years. The focus is on methods that can be applied by practitioners without the need for elaborate experimental requirements. Although the emphasis is on CE, many of the conclusions also apply to microfluidic formats.

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“…In addition, greater care should be taken for air bubble generation and the destabilization of flow caused by either external or internal temperature control. Several measurements of fluid temperature in the microscale apparatus have been reported through the measurement of [84][85][86][87]:…”

Section: Environmental Control In Microfluidic Device For Islet Studymentioning

confidence: 99%

Application of Microfluidic Technology to Pancreatic Islet Research: First Decade of Endeavor

Wang

Mendoza-Elias

et al. 2010

Bioanalysis

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β-cells respond to blood glucose by secreting insulin to maintain glucose homeostasis. Perifusion enables manipulation of biological and chemical cues in elucidating the mechanisms of β-cell physiology. Recently, microfluidic devices made of polydimethylsiloxane and Borofloat glass have been developed as miniaturized perifusion setups and demonstrated distinct advantages over conventional techniques in resolving rapid secretory and metabolic waveforms intrinsic to β-cells. In order to enhance sensing and monitoring capabilities, these devices have been integrated with analytical tools to increase assay throughput. The spatio-temporal resolutions of these analyses have been improved through enhanced flow control, valves and compartmentalization. For the first time, this review provides an overview of current devices used in islet studies and analyzes their strengths and experimental suitability. To realize the potential of microfluidic islet applications, it is essential to bridge the gap in design and application between engineers and biologists through the creation of standardized bioassays and user-friendly interfaces.

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Spatially resolved temperature measurements in electrophoresis capillaries by Raman thermometry

Cited by 54 publications

References 27 publications

Influence of solvent on temperature and thermal peak broadening in capillary zone electrophoresis

Influence of solvent on temperature and thermal peak broadening in capillary zone electrophoresis

Joule heating effects and the experimental determination of temperature during CE

Application of Microfluidic Technology to Pancreatic Islet Research: First Decade of Endeavor

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