Novel ultra stable silica-based stationary phases for reversed phase liquid chromatography-Study of a hydrophobically assisted weak acid cation exchange phase

Yu Zhang, Peter W Carr

Research output: Contribution to journalArticle

27 Scopus citations

Abstract

A mixed-mode reversed-phase/weak cation exchange (RP/WCX) phase has been developed by introducing a small amount of carboxylate functionality into a hydrophobic hyper-crosslinked (HC) platform. This silica-based HC platform was designed to form an extensive polystyrene network completely confined to the particle's surface. The fully connected polymer network prevents the loss of bonded phase, which leads to superior hydrolytic stability of the new phase when compared to conventional silica-based phases. Compared to previously introduced HC phases the added carboxylic groups impart a new weak cation exchange selectivity to the base hydrophobic HC platform. The phase thus prepared shows a mixed-mode retention mechanism, allowing for both neutral organic compounds and bases of a wide polarity range to be simultaneously separated on the same phase under the same conditions. In addition, the new phase offers the flexibility that gradients in organic modifier, pH or ionic competitors can be used to affect the separation of a wide range of solutes. Moreover, the inherent weak acid cation exchange groups allow formic and acetic acid buffers to be used as eluents thereby avoiding the mass spectrometric ionization suppression problems concomitant to the use of non-volatile additives such as strong amine modifiers (e.g. triethylamine) or salts (e.g. NaCl) to elute basic solutes from the strong cation exchange phase which was previously developed in this lab. The use of the new phase for achieving strong retention of rather hydrophilic neurotransmitters and drugs of abuse without the need for ion pairing agents is demonstrated.

Original languageEnglish (US)
Pages (from-to)763-777
Number of pages15
JournalJournal of Chromatography A
Volume1218
Issue number6
DOIs
StatePublished - Feb 11 2011

Keywords

  • Basic analytes
  • Cation exchange
  • HPLC
  • Hydrophobically assisted ion exchange
  • Mixed-mode retention
  • Reversed phase
  • Selectivity
  • Stationary phase

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