Capillary electrochromatography of tricyclic antidepressants on strong cation exchangers with different pore sizes

Enlund, Anna Maria; Isaksson, Roland; Westerlund, Douglas

doi:10.1016/s0021-9673(01)00738-5

Cited by 24 publications

(17 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As the ionic strength increases the thickness of the double layer decreases, i. e. the zeta potential on the surface is reduced, and thus the EOF is lowered. A contrary result was also reported on SCX particulate materials with wide pore sizes by Enlund et al [3], which was ascribed to the generation of flow inside the pores. No bubble formation was observed throughout the CEC experiments on the prepared column, even without applying a pressure to both inlet and outlet.…”

Section: Eof Of the Ms-scx Columnmentioning

confidence: 64%

“…Smith and Evans [2] suggested overcoming this problem by using strong cation-exchange (SCX) particles instead; as such phases could provide a substantial and stable EOF in a much wider pH range due to the low pK a value of the sulfonate group. Capillary electrochromatographic separation of tricyclic antidepressants was carried out by Enlund et al [3] on a column with strong cationexchangers with different pore sizes. Separation of small peptides was also investigated by Ye et al [4] by using SCX packing materials as stationary phase.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Preparation of monolithic silica column with strong cation‐exchange stationary phase for capillary electrochromatography

Xie¹,

Hu²,

Xiao³

et al. 2005

J of Separation Science

View full text Add to dashboard Cite

Preparation of monolithic silica column with strong cation-exchange stationary phase for capillary electrochromatography A monolithic silica based strong cation-exchange stationary phase was successfully prepared for capillary electrochromatography. The monolithic silica matrix from a solgel process was chemically modified by treatment with 3-mercaptopropyltrimethoxysilane followed by a chemical oxidation procedure to produce the desired function. The strong cation-exchange stationary phase was characterized by its substantial and stable electroosmotic flow (EOF), and it was observed that the EOF value of the prepared column remained almost unchanged at different buffer pH values and slowly decreased with increasing phosphate concentration in the mobile phase. The monolithic silica column with strong cation-exchange stationary phase has been successfully employed in the electrochromatographic separation of b-blockers and alkaloids extracted from traditional Chinese medicines (TCMs). The column efficiencies for the tested b-blockers varied from 210,000 to 340,000 plates/m. A peak compression effect was observed for atenolol with the mobile phase having a low phosphate concentration.

show abstract

Section: Eof Of the Ms-scx Columnmentioning

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Preparation of monolithic silica column with strong cation‐exchange stationary phase for capillary electrochromatography

Xie¹,

Hu²,

Xiao³

et al. 2005

J of Separation Science

View full text Add to dashboard Cite

show abstract

“…At low mobile phase pH, high EOF velocities can be realized through the introduction of strong cation-exchange (SCX) functionalities to the stationary phase. This also improves the separation of basic analytes by the dominating ion-exchange mechanism [23][24][25][26][27][28][29][30][31]. Retention in CEC is often assumed to result from independent contributions of the analytes' LC and CZE behavior.…”

Section: Introductionmentioning

confidence: 99%

Electrochromatographic retention of peptides on strong cation‐exchange stationary phases

Nischang¹,

Höltzel²,

Tallarek³

2010

Electrophoresis

View full text Add to dashboard Cite

We analyze the systematic and substantial electrical field-dependence of electrochromatographic retention for four counterionic peptides ([Met5]enkephalin, oxytocin, [Arg8]vasopressin, and luteinizing hormone releasing hormone (LHRH) ) on a strong cation-exchange (SCX) stationary phase. Our experiments show that retention behavior in the studied system depends on the charge-selectivity of the stationary phase particles, the applied voltage, and the peptides' net charge. Retention factors of twice positively charged peptides ([Arg8]vasopressin and LHRH at pH 2.7) decrease with increasing applied voltage, whereas lower charged peptides (oxytocin and [Met5]enkephalin at pH 2.7, [Arg8]vasopressin and LHRH at pH 7.0) show a concomitant increase in their retention factors. The observed behavior is explained on the basis of electrical fieldinduced concentration polarization (CP) that develops around the SCX particles of the packing. The intraparticle concentration of charged species (buffer ions, peptides) increases with increasing applied voltage due to diffusive backflux from the enriched CP zone associated with each SCX particle. For twice charged and on the SCX phase strongly retained peptides the local increase in mobile phase ionic strength reduces the electrostatic interactions with the stationary phase, which explains the decrease of retention factors with increasing applied voltage and CP intensity. Lower charged and weaker retained peptides experience a much stronger relative intraparticle enrichment than the twice-charged peptides, which results in a net increase of retention factors with increasing applied voltage. The CP-related contribution to electrochromatographic retention of peptides on the SCX stationary phase is modulated by the applied voltage, the mobile phase ionic strength, and the peptides' net charge and could be used for selectivity tuning in difficult separations.

show abstract

“…For a fixed grafting density, the EOF generated in capillaries packed with SiNP (nonporous silica particles), Si1000 (silica particles with 1000 Å pore size) and Si100 (silica particles with 100 Å pore size), appears to decrease in the same order. This may tentatively be ascribed to a lower permeability and to the double layer overlap [19,20].…”

Section: Resultsmentioning

confidence: 94%

Molecularly imprinted polymer films grafted from porous or nonporous silica: Novel affinity stationary phases in capillary electrochromatography

et al. 2003

View full text Add to dashboard Cite

Molecularly imprinted composite materials were evaluated as chiral stationary phases in capillary electrochromatography (CEC). These consisted of spherical silica particles of different sizes and of different porosities, containing a surface-immobilized layer of molecularly imprinted polymer (MIP) targeted to bind L-phenylalanine anilide. Fused silica capillaries were packed over a length of 8.5 cm, using a pneumate amplification pump, and the stationary phase thus obtained was tested with respect to its electrochromatographic performance. The electroendosmotic flow (EOF) mobility was evaluated with respect to the content of grafted polymer, as well as the ionic strength and the acetonitrile content of the electrolyte. Moreover, the influence of the layer thickness and of the stationary phase porosity on the performance and on the sample load capacity was investigated. The packings exhibited different relative efficiencies for the two enantiomers. The results were discussed in terms of differencies in accessibility to the binding sites of the packings and of the mechanism of EOF generation. In the wide context of the different approaches so far proposed for MIP stationary phases in CEC, these materials can be a good alternative, worthy of further development and application, not restricted to chiral separations.

show abstract

Capillary electrochromatography of tricyclic antidepressants on strong cation exchangers with different pore sizes

Cited by 24 publications

References 28 publications

Preparation of monolithic silica column with strong cation‐exchange stationary phase for capillary electrochromatography

Preparation of monolithic silica column with strong cation‐exchange stationary phase for capillary electrochromatography

Electrochromatographic retention of peptides on strong cation‐exchange stationary phases

Molecularly imprinted polymer films grafted from porous or nonporous silica: Novel affinity stationary phases in capillary electrochromatography

Contact Info

Product

Resources

About