Size-fractionation of silver nanoparticles using ion-pair extraction in a counter-current chromatograph

Ching Wei Shen, Tiing Yu*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Size separation of silver nanoparticles was investigated in counter-current chromatography (CCC) based on a unique step-gradient extraction process. Carboxylate anions were modified on silver nanoparticles to produce water-dispersible nanoparticles. The aqueous nanoparticles were readily transferred to the organic phase (toluene/hexane = 1:1, v/v) together with the phase transfer catalyst, tetraoctylammonium bromide (TOAB), owing to the ion-pair adduct formation between silver nanoparticle anions and tetraoctylammonium cations. Smaller nanoparticles were found to be more readily transferred to the organic phase compared to larger nanoparticles. Various concentrations of TOAB in the organic elution phase were used in the CCC extraction experiments. It appeared that a concentration of 0.02 mM of TOAB was adequate to achieve optimum separation and recovery for the aqueous Ag nanoparticle sample (1.5 mg) in the CCC extraction experiments. Samples of 15.8 ± 5.3 nm were separated; the distributions of four fractions collected were 13.7 ± 1.9, 14.1 ± 3.5, 19.2 ± 4.3, and 22.2 ± 4.9 nm. Compared with the stepwise extraction performed in this study, the step-gradient extractions using CCC provided much better size discrimination.

Original languageEnglish
Pages (from-to)5962-5967
Number of pages6
JournalJournal of Chromatography A
Volume1216
Issue number32
DOIs
StatePublished - 7 Aug 2009

Keywords

  • Counter-current chromatography
  • Ion-pair
  • Phase transfer
  • Silver nanoparticles
  • Size separation
  • Step-gradient extraction

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