Identification of gonadorelin (LHRH) derivatives: Comparison of reversed-phase high-performance liquid chromatography and micellar electrokinetic chromatography

Corran, Patrick H.; Sutcliffe, Nick

doi:10.1016/0021-9673(93)80060-l

Cited by 30 publications

(9 citation statements)

References 16 publications

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“…[57, 164, 1651, refined in [58, 591). These findings have essentially been confirmed by differences in selectivity reported in other studies [8, 168,177,203,242,2431. This fundamental understanding now makes it possible to give a rational strategy for method development.…”

Section: (7)supporting

confidence: 86%

Strategies for capillary electrophoresis: Method development and validation for pharmaceutical and biological applications

1998

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This review is in support of the development of selective, reproducible and validated capillary electrophoretis (CE) methods. Focusing on pharmaceutical and biological applications, the successful use of CE is demonstrated by more than 800 references, mainly from 1994 until 1998. Approximately 80 recent reviews have been catalogued. These articles sum up the existing strategies for method development in CE, especially in the search for generally accepted concepts, but also looking for new, promising reagents and ideas. General strategies for method development were derived not only with regard to selectivity and efficiency, but also with regard to precision, short analysis time, limit of detection, sample pretreatment requirements and validation. Standard buffer recipes, surfactants used in micellar electrokinetic capillary chromatography (MEKC), chiral selectors, useful buffer additives, polymeric separation media, electroosmotic flow (EOF) modifiers, dynamic and permanent coatings, actions to deal with complex matrices and aspects of validation are collected in 20 tables. Detailed schemes for the development of MEKC methods and chiral separations, for optimizing separation efficiency, means of troubleshooting, and other important information for key decisions during method development are given in 19 diagrams. Method development for peptide and protein separations, possibilities to influence the EOF and how to stabilize it, as well as indirect detection are considered in special sections.

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Section: (7)supporting

confidence: 86%

Strategies for capillary electrophoresis: Method development and validation for pharmaceutical and biological applications

1998

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“…Electrophoretic mobilities were determined by CZE experiments using the mobile phase Electrophoresis 2010, 31, 933-943 composition of the LC and subsequent CEC experiments and agree well with literature data based on purely aqueous CZE buffers [58][59][60][61]. All peptides bear a positive net charge at pH 2.7.…”

supporting

confidence: 76%

Electrochromatographic retention of peptides on strong cation‐exchange stationary phases

Nischang¹,

Höltzel²,

Tallarek³

2010

Electrophoresis

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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.

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“…It should, however, be noted that separation systems based solely on electrically neutral detergents cannot strictly be classed as MEKC as the micelles themselves do not actively migrate and analyte transport occurs by electrophoretic migration with contributions from EOF [24]. The general utility of these agents as chiral selectors, using a range of structurally diverse analytes, is currently under investigation.…”

Section: Discussionmentioning

confidence: 99%

Use of chiral zwitterionic surfactants for enantiomeric resolutions by capillary electrophoresis

2003

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The enantiomeric resolution of 1,1'-binaphthyl-2,2'-diamine and Tröger's base was investigated using the commercially available zwitterionic surfactants 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulphonate (CHAPS) and 3-[(3-cholamidopropyl)dimethylammonio]-2-hydroxy-1-propanesulphonate (CHAPSO). Resolution of the weakly basic chiral probes was achieved using varying concentrations of surfactant, above their critical micellar concentrations, in a phosphate buffer (pH 2.5; 100 mM) to ensure ionisation of the analytes. Both CHAPS and CHAPSO were employed in the absence of additional coselectors or surfactants as sole micellar-forming agents. The addition of organic modifiers, methanol and acetonitrile (ACN), to the background electrolyte (BGE) was found to have a detrimental effect on enantioselectivity presumably by alteration of the phase polarity.

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Identification of gonadorelin (LHRH) derivatives: Comparison of reversed-phase high-performance liquid chromatography and micellar electrokinetic chromatography

Cited by 30 publications

References 16 publications

Strategies for capillary electrophoresis: Method development and validation for pharmaceutical and biological applications

Strategies for capillary electrophoresis: Method development and validation for pharmaceutical and biological applications

Electrochromatographic retention of peptides on strong cation‐exchange stationary phases

Use of chiral zwitterionic surfactants for enantiomeric resolutions by capillary electrophoresis

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