Ion-pair chromatographic separation of water-soluble gold monolayer-protected clusters

Martin M F CHOI, Alicia D. Douglas, Royce W. Murray*

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

69 Citations (Scopus)


We demonstrate the efficacy of ion-pair chromatography for separations of samples of charged, polydisperse, water-soluble gold nanoparticles protected by monolayers of N-acetyl-L-cysteine and of tiopronin ligands. These nanoparticle mixtures have 1-2-nm-diameter Au core sizes as estimated from UV-visible spectra of the separated components. This size range encompasses the transition from bulk metal to molecular properties. The nanoparticle mixtures were resolved, the smallest nano-particles eluting first, on an octadecylsilyl (C18) column using isocratic elution with a methanol/water mobile phase containing tetrabutylammonium fluoride (Bu4N+F-) and phosphate buffer. The column retention increases with Bu4N +F- concentration, lowered pH, and decreasing methanol volume fraction. The retention mechanism is dominated by ion-pairing in either the mobile phase or at the stationary/mobile-phase interface. Size exclusion effects, used in many previous nanoparticle separations, are insignificant.

Original languageEnglish
Pages (from-to)2779-2785
Number of pages7
JournalAnalytical Chemistry
Issue number8
Publication statusPublished - 15 Apr 2006

Scopus Subject Areas

  • Analytical Chemistry


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