Semi-quantitative determination of cationic surfactants in aqueous solutions using gold nanoparticles as reporter probes

Chi Lap Kuong, Wei Yu Chen, Yu-Chie Chen*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

Concentrations of cationic surfactants in aqueous solutions have been estimated on the basis of changes in the color of gold nanoparticles, used as reporter probes. We have shown that the colors of gold nanoparticles with anionic protective groups on their surfaces shift from red to indigo/purple and then back to red in a range of cationic surfactant solutions in which concentrations vary from very low to above the theoretical CMCs. The color changes occur near the theoretical CMCs, presumably because the presence of surfactant micelles in the solution prevents the gold nanoparticles from aggregating. We have used gold nanoparticles as reporter probes to determine the concentrations of cationic surfactants in products such as hair conditioners, which often contain large amounts of alkyltrimethylammonium halides. Although this approach can only provide an estimate, it can be performed simply by addition of a given amount of gold nanoparticles to a series of diluted solutions, without the need for instruments or labor-intensive procedures. [Figure not available: see fulltext.].

Original languageAmerican English
Pages (from-to)2091-2099
Number of pages9
JournalAnalytical and Bioanalytical Chemistry
Volume387
Issue number6
DOIs
StatePublished - 1 Mar 2007

Keywords

  • Cationic surfactants
  • Chemical sensor
  • Gold nanoparticles
  • Iron oxide particles
  • SALDI MS

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