Dependence of electroosmotic flow in capillary electrophoresis on Group I and II metal ions

Dickens, Jason E.; Gorse, J.; Everhart, J.A.; Ryan, Martin J.

doi:10.1016/0378-4347(94)00074-3

Cited by 28 publications

(15 citation statements)

References 13 publications

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“…This suggests that the transient is related to a physical equilibration phenomenon at the fluid-solid interface. Our value for z/pC in silica microchannels, À27.0 mV, also agrees with those from experiments found in the literature [34,[53][54][55], though its magnitude is at the low end of the range of reported values (Table 2) [34]. The long-time-scale decay observed here in TOPAS microchannels and previously in PTFE microchannels [8] is related to a slow equilibration process at the fluid-solid interface, and this particular form of transient is likely to be unique to hydrophobic surfaces, as similar transients were not observed in silica microchannels.…”

Section: Time-resolved Electrokinetic Measurements In Pressure-drivensupporting

confidence: 92%

Transient ζ‐potential measurements in hydrophobic, TOPAS microfluidic substrates

2009

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We utilize time-resolved electrokinetic measurements in order to study the electrokinetic properties of silica and TOPAS microfluidic channels as a function of the time history of the fluid-solid interface. In pressure-driven flow through TOPAS microchannels, the zeta-potential as inferred from streaming potential measurements decays exponentially by a factor of 1.5 with a characteristic decay time of 3 h after the initial formation of the fluid-solid interface. A similar exponential decay is observed immediately after water is exchanged for ethanol as the solvent in the system. In electroosmotically driven flow through TOPAS microchannels, the zeta-potential as inferred through current monitoring experiments was constant in time. No electrokinetic transients were observed in silica microchannels under these flow conditions.

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Section: Time-resolved Electrokinetic Measurements In Pressure-drivensupporting

confidence: 92%

Transient ζ‐potential measurements in hydrophobic, TOPAS microfluidic substrates

2009

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“…(9) is often not enough to describe valency effects, since many results show much more dramatic z reduction due to specific adsorption [63,66,67]. Reports vary as to whether variations with ion size among ions with common valency are well correlated [20,63,68,69]; regardless, these variations are typically small as compared to experimental uncertainty and investigator-to-investigator scatter.…”

Section: Dependence Of Ae On Counterion Valency and Sizementioning

confidence: 94%

Zeta potential of microfluidic substrates: 1. Theory, experimental techniques, and effects on separations

2004

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This paper summarizes theory, experimental techniques, and the reported data pertaining to the zeta potential of silica and silicon with attention to use as microfluidic substrate materials, particularly for microchip chemical separations. Dependence on cation concentration, buffer and cation type, pH, cation valency, and temperature are discussed. The Debye-Hückel limit, which is often correctly treated as a good approximation for describing the ion concentration in the double layer, can lead to serious errors if it is extended to predict the dependence of zeta potential on the counterion concentration. For indifferent univalent electrolytes (e.g., sodium and potassium), two simple scalings for the dependence of zeta potential on counterion concentration can be derived in high- and low-zeta limits of the nonlinear Poisson-Boltzman equation solution in the double layer. It is shown that for most situations relevant to microchip separations, the high-zeta limit is most applicable, leading to the conclusion that the zeta potential on silica substrates is approximately proportional to the logarithm of the molar counterion concentration. The zeta vs. pH dependence measurements from several experiments are compared by normalizing the zeta based on concentration.

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“…Optimum separation of propranolol required the use of potassium phosphate, rather than sodium phosphate as the buffer component, and the addition of tetramethyl ammonium phosphate. The tetramethyl ammonium phosphate and potassium ions most probably helped resolution by reducing analyte-wall interactions and lowering electro-osmotic flow (Quang and Khaledi, 1993;Dickens et al, 1994).…”

Section: Resultsmentioning

confidence: 98%

Chiral Separations of Enantiomeric Pharmaceuticals by Capillary Electrophoresis Using Sulphobutyl Ether ?-Cyclodextrin as Isomer Selector

Xie

Skanchy

Stobaugh

1997

Biomed. Chromatogr.

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Dependence of electroosmotic flow in capillary electrophoresis on Group I and II metal ions

Cited by 28 publications

References 13 publications

Transient ζ‐potential measurements in hydrophobic, TOPAS microfluidic substrates

Transient ζ‐potential measurements in hydrophobic, TOPAS microfluidic substrates

Zeta potential of microfluidic substrates: 1. Theory, experimental techniques, and effects on separations

Chiral Separations of Enantiomeric Pharmaceuticals by Capillary Electrophoresis Using Sulphobutyl Ether ?-Cyclodextrin as Isomer Selector

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