Electrostatic ion chromatography

Hu, Wenzhi; Takeuchi, Toyohide; Haraguchi, Hiroki

doi:10.1021/ac00065a007

Cited by 125 publications

(96 citation statements)

References 3 publications

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“…The latter feature is particularly evident in the technique of electrostatic ion chromatography (EIC) [65][66][67][68] in which an octadecylsilica reversed-phase material is treated with a hydrophobic zwitterionic surfactant in which the positively and negatively charged functional groups are usually separated by three carbon atoms. Suitable surfactants are shown in Fig.…”

Section: Ion-exchangers With Covalently Attached or Physically Adsorbmentioning

confidence: 99%

Zwitterionic Ion-Exchangers in Liquid Chromatography

Nesterenko

Haddad

2000

ANAL. SCI.

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The idea of combining both anion-and cation-exchange groups in a single particle of ion-exchange resin for the purpose of improvement of ion-exchange selectivity appeared shortly after the invention of polymeric ion-exchange resins. Stach 1 synthesised a zwitterionic ion-exchange resin containing both sulfonic acid and quaternary ammonium functional groups in 1951. This material was obtained by copolymerization of styrene and vinylchloride, followed by the introduction of quaternary ammonium functional groups by reaction of chloro-groups with trimethylamine, and then sulfonation with sulfuric acid to give sulfonic acid groups. However this first zwitterionic exchange resin was not fully characterized and its physico-chemical properties and performance were not evaluated. Originally, phenolformaldehyde polycondensation type resins were very popular and the occurrence of anion-exchange functional groups and residual phenol groups provided some zwitterionic properties for this material in alkaline media where the phenol group was dissociated. These resins had a monotonic distribution of functional groups over the entire volume of the resin. Since 1951 the approaches to the synthesis and design of zwitterionic ion-exchangers were directed towards localization of the oppositely charged groups in a bonded layer on the surface of the particle or on attached molecules.Zwitterionic ion-exchangers are considered to include only those materials that contain the charged groups in a single particle, rather than mixed-bed ion-exchangers where a mixture of cation-and anion-exchangers is used. However, agglomerated ion-exchangers containing a layer of electrostatically retained microbeads around a core particle of opposite charge fall under the scope of this review. In some sources of literature the terms amphoteric and bipolar ion-exchangers have been also used. 2The distribution of the oppositely charged groups can vary considerably and the following types of zwitterionic ionexchangers can be identified: (i) Polyampholyte resins having a continuous distribution of oppositely charged groups in the whole volume of the ionexchange particle. (ii) Pellicular resins containing a layer of opposite charge on a charged core particle, with this layer comprising microparticles, latex microbeads, a polymer film, or a simple treated outer surface of the core (e.g. sulfonated), for the purpose of adding functional groups of opposite charge sign to the functional groups on the core. Zwitterionic ion-exchangers represent a new direction in the development of stationary phases for different modes of high-performance liquid chromatography. The combination of positively and negatively charged sites in a single particle, or within the functional groups of a single molecule attached to the surface of an adsorbent, provides unique opportunities to vary the selectivity of separation. The classification of zwitterionic ion-exchangers based on their structure, distribution of oppositely charged groups, and their applications is considered.

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Section: Ion-exchangers With Covalently Attached or Physically Adsorbmentioning

confidence: 99%

Zwitterionic Ion-Exchangers in Liquid Chromatography

Nesterenko

Haddad

2000

ANAL. SCI.

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“…The stationary phase of electrostatic ion chromatography (EIC) [35] is obtained by hydrophobic adsorption of zwitterionic compounds on the reverse phase. It means that both positive and negative ions are present in the stationary phase.…”

Section: Electrostatic Ion Chromatographymentioning

confidence: 99%

“…Amino acids can be easily separated by electrostatic ion chromatography [35]. Their retention is proportional to their isoelectric point and also to the length of their aliphatic chains and the content of aromatic groups in the molecule.…”

Section: Electrostatic Ion Chromatographymentioning

confidence: 99%

“…This behavior resembles that of amino acid separation by ion exclusion chromatography. Similar to IEC [7], cations and anions can be separated in EIC in one single chromatographic run [35]. Divalent ions are eluted earlier (screening effect) than monovalent ones, if the solute is retained according to the ion exclusion retention mechanism, or later (electrostatic attraction) if the ion exchange mode is used [1].…”

Section: Electrostatic Ion Chromatographymentioning

confidence: 99%

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A theoretical explanation for the retention mechanism of ion exclusion chromatography

Głód¹,

Baumann

2003

J of Separation Science

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A theoretical explanation for the retention mechanism of ion exclusion chromatography Ion Exclusion Chromatography is classically used for the separation of weak acid anions. Dilute strong acids (e.g. sulphuric or perchloric acid) or just water are used as eluents. To increase the exclusion effect, strong cation exchangers, characterized by high concentration of functional groups, are applied. The inner column volume of commercially available columns is increased by increasing their size in comparison to traditional ones (usually 30067.8 mm ID). The description of the retention mechanism of this technique implicitly assumes that both mobile and stationary phases are typical aqueous solutions, and their dielectric constants are thus equal. This equality implies the equality of solute dissociation constants in both phases. Another implicit assumption is that the dead-and inner volumes of the column are constant, and independent of the mobile phase composition. The present paper shows that stationary and mobile phases are generally characterized by different physicochemical parameters. Thus, they cannot be considered as regular aqueous solutions. Additionally, we show that weak cation exchanger resins, which are characterized by a relatively small concentration of the functional groups, and weak acid based buffers can also be used in IEC. This would expand the possible applications of this method and enable, for example, the separation of strong acids (anions). The influence of ionic strength on the retention and dead-and inner column volumes is also discussed. Finally we also briefly describe the retention mechanism of Electrostatic Ion Chromatography.

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“…The zwitterionic surfactant, C14N3S, is also well-known as a coating reagent on ODS for electrostatic ion chromatography (EIC). 2,3 Since the ODS-coated C14N3S and the C14N3S micelles as its stationary phase produced a separation site like an ionexchanger, the separation mechanism of ions depended on the ionic association and on the hydrophobic interaction between C14N3S and the ions. 4,5 The crystal structure of C14N3S would be useful in determining the separation mechanism with the geometry of C14N3S.…”

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confidence: 99%