Resolution in capillary electrophoresis with nonaqueous methanol as solvent: Theoretical prediction and experimental confirmation

Porras, Simo P.; Riekkola, Marja‐Liisa; Kenndler, Ernst

doi:10.1002/1522-2683(200109)22:17<3798::aid-elps3798>3.0.co;2-a

Cited by 26 publications

(17 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(12). This approach has been used in methanolic BGEs to determine pK a values of cation acids [54], neutral acids [55] and zwitterionic peptides [56] by using buffers prepared from acids given in Table 3. An example of pH adjustment in MeOH can be seen in Fig.…”

Section: Methanol As Solventmentioning

confidence: 99%

Capillary zone electrophoresis in non-aqueous solutions: pH of the background electrolyte

Porras

Kenndler

2004

Journal of Chromatography A

Self Cite

View full text Add to dashboard Cite

Section: Methanol As Solventmentioning

confidence: 99%

Capillary zone electrophoresis in non-aqueous solutions: pH of the background electrolyte

Porras

Kenndler

2004

Journal of Chromatography A

Self Cite

View full text Add to dashboard Cite

“…Note that the method relies on the constant pressure during transportation, and therefore the pressure control system of the HP 3D CE equipment needed to be slightly modified [9]. All electrophoretic mobilities were determined in three replicate runs.…”

Section: Measurement Of Electrophoretic Mobilitiesmentioning

confidence: 99%

“…The pK a values of the selected model analytes (benzoic acids and phenols, see Table 1) are # 4.1 in water [12,13] and # 8.48 in MeOH [9,13]. Thus, a phosphate buffer at pH 7.03 is suitable for mobility measurements of fully ionized analytes in aqueous media.…”

Section: Selection Of Experimental Conditionsmentioning

confidence: 99%

“…According to the Henderson-Hasselbalch equation, the pH* of this solution is 10.4 (see Section 2.4 for details). The pK a * value of 2,4-dihydroxybenzoic acid in MeOH is 8.48 [9]. For this acid the electrophoretic mobility was determined also at pH* 10.7, and the mobilities at both pH* were the same within the experimental error, confirming full ionization also at pH* 10.4 in MeOH.…”

Section: Selection Of Experimental Conditionsmentioning

confidence: 99%

See 1 more Smart Citation

Capillary electrophoresis of anionic analytes in methanol: Effect of counter-ions on electrophoretic mobility

2002

Self Cite

View full text Add to dashboard Cite

Mobilities of 11 substituted benzoates and 3 nitrophenolates were determined in non-aqueous methanol with Li+, Na+, K+, Rb+, and tetrabutylammonium (Bu4N+) as counter-ions of the background electrolyte. The influence of the ionic concentration of the background electrolyte on the mobility of the analyte anions is more pronounced compared to aqueous solutions. The deviation from the dependence of the mobilities on the ionic strength from the Debye-Hückel-Onsager theory indicates the occurrence of ion-pair formation. For a given ion concentration (10 mmol/L), the decrease of the analyte mobility follows the counter-ion sequence Li+ < Na+ < K+ < Rb+, which is the inverse order of their Stokes radii. Bu4N+ as counter-ion has a similar effect on the analyte mobility than Li+ (which has the same Stokes radius, but a six times smaller crystal radius). Exceptions are some di- and trihydroxybenzoates. The mobilities in methanol and in water with the same counter-ion (Na+) at a given ionic concentration show very low correlation.

show abstract

“…These investigations included the research on the effects of solvents on the z potential of interfaces between the BGE and the capillary wall, and the changes of the electroosmotic flow (EOF) mobility [18,19]. The shift of pK a values upon transformation of the acid-base equilibria from water into organic or mixed aqueous-organic solvents, and the effect of the solvent on the ionic mobility was the topic of a series of more recent papers [20][21][22][23][24][25][26][27][28][29][30][31].…”

Section: Introductionmentioning

confidence: 99%

Electrophoretic mobilities of large organic ions in nonaqueous solvents: Determination by capillary electrophoresis in propylene carbonate, N,N-dimethylformamide, N,N,-dimethylacetamide, acetonitrile and methanol

et al. 2002

Self Cite

View full text Add to dashboard Cite

The mobilities of the monocharged permanent tertraphenylphosphonium cation and tetraphenylborate anion are determined by capillary zone electrophoresis in different organic solvents as a function of the ionic strength, I, of the background electrolyte. The nonaqueous solvents are propylene carbonate (PC), N,N-dimethylformamide (DMF), N,N,-dimethylacetamide (DMA), acetonitrile (MeCN) and methanol (MeOH). The ionic strength is between 5 and 50 mmol/L. The mobility as a function of I is in good agreement with the theory of Debye, Hückel and Onsager (DHO), extended by the ion size parameter as introduced by Falkenhagen and Pitts. The values of the limiting DHO slopes of the mobility vs. I curves (the slopes express the influence of the solvent on the reduction of the mobility with increase of I) decrease in the order MeCN > MeOH > DMF > DMA > PC. Absolute mobilities (obtained by extrapolation to I = 0) of a particular ion differ by a factor of about 7 between the solvents. However, constancy within 10% is observed for their Walden products (the absolute mobility multiplied with the solvent's macroviscosity). The role of dielectric friction on the mobility of the present monocharged, large analyte ions is discussed according to the theory of Hubbard and Onsager. Based on the radii of the ions, the static permittivity of the solvent and its permittivity at infinite frequency, and the relaxation time of polarization, an equal contribution of dielectric and hydrodynamic friction is predicted in MeOH as solvent. Experimental data are in contrast to this prediction, indicating the overestimation of dielectric friction, and the dominance of hydrodynamic friction on the migration of the analyte ions in all solvents under consideration.

show abstract

Resolution in capillary electrophoresis with nonaqueous methanol as solvent: Theoretical prediction and experimental confirmation

Cited by 26 publications

References 15 publications

Capillary zone electrophoresis in non-aqueous solutions: pH of the background electrolyte

Capillary zone electrophoresis in non-aqueous solutions: pH of the background electrolyte

Capillary electrophoresis of anionic analytes in methanol: Effect of counter-ions on electrophoretic mobility

Electrophoretic mobilities of large organic ions in nonaqueous solvents: Determination by capillary electrophoresis in propylene carbonate, N,N-dimethylformamide, N,N,-dimethylacetamide, acetonitrile and methanol

Contact Info

Product

Resources

About