ADSORPTIVE STRIPPING VOLTAMMETRY OF ANIONIC SURFACTANTS ON A CARBON-PASTE ELECTRODE USING FERROCENYL CATIONIC SURFACTANT AS AN ANALYTICAL ELECTROCHEMICAL PROBE

Adsorption stripping voltammetry (AdSV) for anionic surfactants was ex amined, based on ion association with an electroactive ferrocenyl cati onic surfactant. The ion association complex between an anionic surfac tant and a ferrocenyl cationic surfactant accumulated on the carbon pa ste electrode (CPE) in the absence of an applied potential. The concen tration of anionic surfactant was indirectly evaluated from the oxidat ion wave of the ferrocenyl cationic surfactant. By means of AdSV, leve ls of anionic surfactants of 10(-7) mol dm(-3) could be measured with good selectivity. The role of pasting liquids on the accumulation beha vior of ferrocenyl TMA were examined by a comparison of two pasting li quids. The first, 2-nitrophenyl octyl ether (NPOE) was capable of extr acting the ferrocenyl TMA salt, while the other, di-n-octylphthalate ( DOP) was not. The voltammograms of ferrocenyl TMA varied considerably with the pasting liquids. In particular, the peak potentials at NPOE-C PE gradually shifted with time, as a result of the extraction of the f errocenyl TMA salt into the CPE. However, the peak potential at DOP-CP E remained constant.