Change of pH in electrophoretic zones as a cause of peak deformation

Xu, X.; Kok, Wim Th.; Poppe, H.

doi:10.1016/0021-9673(96)00236-1

Cited by 55 publications

(46 citation statements)

References 20 publications

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“…Poppe et al [13] derived that electromigration dispersion occurs due to both the conductivity and pH effects. They showed that there even exist compositions of BGEs where the conductivity and pH terms are non-zero, but cancel.…”

Section: Introductionmentioning

confidence: 99%

Conductivity detection in capillary zone electrophoresis: Inspection by PeakMaster

et al. 2005

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A simple rule stating that the signal in conductivity detection in capillary zone electrophoresis is proportional to the difference between the analyte mobility and mobility of the background electrolyte (BGE) co-ion is valid only for systems with fully ionized electrolytes. In zone electrophoresis systems with weak electrolytes both conductivity signal and electromigration dispersion of analyte peaks depend on the conductivity and pH effects. This allows optimization of the composition of BGEs to give a good conductivity signal of analytes while still keeping electromigration dispersion near zero, regardless of the injected amount of sample. The demands to achieve minimum electromigration dispersion and high sensitivity in conductivity detection can be accomplished at the same time. PeakMaster software is used for inspection of BGEs commonly used for separation of sugars (carbohydrates, saccharides) at highly alkaline pH. It is shown that the terms direct and indirect conductivity detection are misleading and should not be used.

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Section: Introductionmentioning

confidence: 99%

Conductivity detection in capillary zone electrophoresis: Inspection by PeakMaster

et al. 2005

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“…(3), buffer concentration has a critical effect on the EMD [16,45]. Figure 2 and Table 3 show the effect of increasing the concentration of lithium phosphate (pH 7.0) buffer for preparative (40 pmol of each protein) injections.…”

Section: Effect Of Buffer Concentrationmentioning

confidence: 97%

“…The triangular peak shape indicates that the broadening at higher analyte concentrations is dominated by electromigration dispersion (EMD) [45,46]. EMD results from differences in the local electric field strength in the analyte zone relative to that in the normal buffer [47].…”

Section: Effect Of Analyte Concentration Under Preparative Conditionsmentioning

confidence: 98%

“…EMD results from differences in the local electric field strength in the analyte zone relative to that in the normal buffer [47]. EMD originates from the difference in the effective mobilities between the analyte and the buffer co-ion and becomes more significant at higher sample concentrations [45]. When the mobility of the analyte molecules is less than that of the buffer co-ions the electric field within the sam- Fig.…”

Section: Effect Of Analyte Concentration Under Preparative Conditionsmentioning

confidence: 99%

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Preparative capillary zone electrophoresis using a dynamic coated wide‐bore capillary

Yassine

Lucy

2006

Electrophoresis

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Preparative capillary zone electrophoresis separations of cytochrome c from bovine and horse heart are performed efficiently in a surfactant-coated capillary. The surfactant, dimethylditetradecylammonium bromide (2C(14)DAB), effectively eliminated protein adsorption from the capillary surface, such that symmetrical peaks with efficiencies of 0.7 million plates/m were observed in 50-microm id capillaries when low concentrations of protein were injected. At protein concentrations greater than 1 g/L, electromigration dispersion became the dominant source of band broadening and the peak shape distorted to triangular fronting. Matching of the mobility of the buffer co-ion to that of the cytochrome c resulted in dramatic improvements in the efficiency and peak shape. Using 100 mM bis(2-hydroxyethyl)imino-tris(hydroxymethyl)methane phosphate buffer at pH 7.0 with a 100-microm id capillary, the maximum sample loading capacity in a single run was 160 pmol (2.0 microg) of each protein.

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“…However, this is an oversimplification as demonstrated in the works of the groups of Beckers, Boč ek, Gaš , Poppe, and Vigh (see, e.g., reviews [35][36][37][38] dealing with such dispersion phenomena). An approximation for the plate height due to electromigration dispersion was described by Xu et al [39]:…”

Section: Peak-broadening Due To Electromigration Dispersionmentioning

confidence: 99%

Are the asserted advantages of organic solvents in capillary electrophoresis real? A critical discussion

Porras

Kenndler

2005

Electrophoresis

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Are the asserted advantages of organic solvents in capillary electrophoresis real? A critical discussionBackground electrolytes (BGEs) prepared in pure organic solvents are common alternatives to aqueous BGEs in capillary electrophoresis. Several general advantages of organic solvents over water have been asserted in the literature, namely (i) organic solvents increase the separation selectivity; (ii) organic solvents increase the separation efficiency; (iii) high separation voltages and/or high BGE ionic strengths can be used in organic solvents due to lower electric current compared to water. Related assumptions are that (iv) due to higher field strengths applicable in organic solvents the analysis time is shorter than in aqueous BGEs, and (v) the solubility and/or stability of components (either analytes or BGE chemicals) is higher/better in organic solvents. In the present work, these asserted advantages were critically evaluated based on the physical principles of ion transport and zone dispersion in solution. The result was that many of the above-mentioned general advantages are overestimated or even inexistent; often they have no fundamental basis.

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Change of pH in electrophoretic zones as a cause of peak deformation

Cited by 55 publications

References 20 publications

Conductivity detection in capillary zone electrophoresis: Inspection by PeakMaster

Conductivity detection in capillary zone electrophoresis: Inspection by PeakMaster

Preparative capillary zone electrophoresis using a dynamic coated wide‐bore capillary

Are the asserted advantages of organic solvents in capillary electrophoresis real? A critical discussion

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