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Updated: Jan 31, 2026

Synthesis, Assembly, and Characterization of Monolayer Protected Gold Nanoparticle Films for Protein Monolayer Electrochemistry
Published on: October 4, 2011
HPLC of Monolayer-Protected Gold Clusters with Baseline Separation
Stefan Knoppe1,2, Pascal Vogt1
1Institute of Physical Chemistry , University of Stuttgart , Pfaffenwaldring 55 , 70569 Stuttgart , Germany.
Abstract:
The properties of ultrasmall metal nanoparticles (ca. 10-200 metal atoms), or monolayer-protected metal clusters (MPCs), drastically depend on their atomic structure. For systematic characterization and application, assessment of their purity is of high importance. Currently, the gold standard for purity control of MPCs is mass spectrometry (MS). Mass spectrometry, however, cannot always detect small impurities; MS of certain clusters, for example, ESI-TOF of Au40(SR)24, is not successful at all. We here present a simple reversed-phase HPLC method for purity control of a series of small alkanethiolate-protected gold clusters. The method allows the detection of small impurities with high sensitivity. Linear correlation between alkyl chain length of Au25(SC nH2 n+1)18 clusters ( n = 6, 8, 10, 12) and their retention time was noticed.
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