Determination of homologues of quaternary ammonium surfactants by capillary electrophoresis using indirect UV detection

Hsueh Ying Liu, Wang Hsien Ding

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51 Scopus citations

Abstract

This investigation describes the simultaneous separation of two major non-chromophoric quaternary ammonium surfactants, alkyltrimethyl- and dialkyldimethylammonium compounds (ATMACs and DADMACs, respectively), by capillary electrophoresis (CE) using indirect UV detection. The most effective separation conditions was 10mM phosphate buffer with 57.5% tetrahydrofuran and 3mM sodium dodecyl sulfate (SDS) at pH 4.3, and the sample hydrodynamic injection of up to 20s at 1psi (approximately 60nl), and an applied voltage of 25kV (1psi=6.9kPa). Specially, the selection of an appropriate chromophore and an internal standard (I.S.) to improve the peak identification and quantitation was systematically investigated. Decylbenzyldimethyl ammonium chloride (C 10-BDMA+C-) as a chromophore with 3mM sodium dodecyl sulfate provided the best detectability for all homologues. The reproducibility of the migration time and quantitative analysis can be improved by using tetraoctyl ammonium ion as an internal standard, giving the relative standard deviation (R.S.D.) less than 0.8% for the relative migration times, and 2.5-5.5% for the relative peak areas. A good linearity of CE analysis was obtained in the range of 1.0-20μg/ml with r2 values of above 0.999. The analysis of cationic surfactants in commercial products of hair conditioners and fabric softeners was also performed. Electrospray mass spectrometric method was applied to evaluate the CE method, and the compatible results were obtained.

Original languageEnglish
Pages (from-to)303-312
Number of pages10
JournalJournal of Chromatography A
Volume1025
Issue number2
DOIs
StatePublished - 6 Feb 2004

Keywords

  • Quaternary ammonium compounds
  • Surfactants

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