Enhancement of electroosmotic flow using zwitterionic additives

MacDonald, Amy M.; Sheppard, Mary A. W.; Lucy, Charles A.

doi:10.1002/elps.200500431

Cited by 16 publications

(6 citation statements)

References 49 publications

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“…The effect of CSL on the other properties of materials has also been studied, including adsorbed protein conformation, 12 mobility of ionic group, 13 thermal stability of the material, 14 adsorption at the air−water interface, 15 and electroosmotic flow. 16 These observations offer solid proofs about the important roles of CSL.…”

Section: Introductionmentioning

confidence: 81%

“…More recently, Mi et al showed different binding behaviors of divalent cations for CB-based materials with different CSLs, leading to different interactions with polysaccharides outside bacteria. The effect of CSL on the other properties of materials has also been studied, including adsorbed protein conformation, mobility of ionic group, thermal stability of the material, adsorption at the air–water interface, and electroosmotic flow . These observations offer solid proofs about the important roles of CSL.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Carbon Spacer Length on Zwitterionic Carboxybetaines

2013

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Zwitterionic carboxybetaines (CBs) are ubiquitous in nature and considered promising materials for biological and chemical applications. A thorough understanding of the effect of carbon spacer length (CSL) on molecular properties is important. In this work, using molecular dynamics simulation and quantum chemical calculation, we investigated the effect of CSL on the molecular properties of CB molecules. The hydration number, structure, and dynamics of carboxylic and trimethyl ammonium groups were investigated and found to present different behaviors in regards to the variation of CSL. The simulation results with partial charges developed from quantum chemical calculations were compared with those with partial charges from the OPLS all atom (OPLSAA) force field. The hydration free energy of CB molecules and CB-Na(+) association was also studied as a function of CSL.

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Section: Introductionmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Effect of Carbon Spacer Length on Zwitterionic Carboxybetaines

2013

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“…In the work of MacDonald et al . the authors reported that zwitterionic additives to the BGE increase the EOF due to an increase of the dielectric constant of the solutions . Overall, the highly negative EOF with Good's buffer BGEs is promising for fast CE analysis of negative compounds.…”

Section: Resultsmentioning

confidence: 99%

Novel cationic polyelectrolyte coatings for capillary electrophoresis

et al. 2015

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The use of bare fused silica capillary in CE can sometimes be inconvenient due to undesirable effects including adsorption of sample or instability of the EOF. This can often be avoided by coating the inner surface of the capillary. In this work, we present and characterize two novel polyelectrolyte coatings (PECs) poly(2-(methacryloyloxy)ethyl trimethylammonium iodide) (PMOTAI) and poly(3-methyl-1-(4-vinylbenzyl)-imidazolium chloride) (PIL-1) for CE. The coated capillaries were studied using a series of aqueous buffers of varying pH, ionic strength, and composition. Our results show that the investigated polyelectrolytes are usable as semi-permanent (physically adsorbed) coatings with at least five runs stability before a short coating regeneration is necessary. Both PECs showed a considerably decreased stability at pH 11.0. The EOF was higher using Good's buffers than with sodium phosphate buffer at the same pH and ionic strength. The thickness of the PEC layers studied by quartz crystal microbalance was 0.83 and 0.52 nm for PMOTAI and PIL-1, respectively. The hydrophobicity of the PEC layers was determined by analysis of a homologous series of alkyl benzoates and expressed as the distribution constants. Our result demonstrates that both PECs had comparable hydrophobicity, which enabled separation of compounds with log Po/w > 2. The ability to separate cationic drugs was shown with β-blockers, compounds often misused in doping. Both coatings were also able to separate hydrolysis products of the ionic liquid 1,5-diazabicyclo[4.3.0]non-5-ene acetate at highly acidic conditions, where bare fused silica capillaries failed to accomplish the separation.

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“…Zwitterions are unique buffers in that they possess a positive and negative charge on the same molecule. They can be used for the prevention of protein adsorption onto the capillary surface , for the complexation of inorganic dianions , and are common buffer additives because of their ability to improve a separation without increasing the ionic strength of the separation buffer . Additionally, zwitterionic buffers can be beneficial to use over other buffers because they can endure the effects of prolonged electrolysis more effectively .…”

Section: Resultsmentioning

confidence: 99%

Adsorption of buffer ion pairs can alter long‐term electroosmotic flow stability

Morris

Harrison

2013

Electrophoresis

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Dynamic capillary coatings have become widespread due to their efficacy in modifying the EOF in capillary electrophoretic separations and ability to limit unwanted analyte-surface interactions. However, our understanding of exactly what types of interactions are taking place at the surface of a capillary when these dynamic additives are present is limited. In this work, we have chosen a simple, small molecule additive, tetramethylammonium to examine its influence on the EOF under typical separation conditions. What we have revealed is that this simple compound does not interact with the capillary surface in a very simple manner. Our initial hypothesis of a direct ionic interaction with the silanol surface has evolved with evidence of complex ion pairing between the silanols, the tetramethylammonium, and the buffer ions. This ion pairing can result in drastic changes in the EOF over time, and that the EOF can only be restored to initial levels with harsh rinses containing sodium hydroxide.

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Enhancement of electroosmotic flow using zwitterionic additives

Cited by 16 publications

References 49 publications

Effect of Carbon Spacer Length on Zwitterionic Carboxybetaines

Effect of Carbon Spacer Length on Zwitterionic Carboxybetaines

Novel cationic polyelectrolyte coatings for capillary electrophoresis

Adsorption of buffer ion pairs can alter long‐term electroosmotic flow stability

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