A method was developed for the analysis of a number of surfactants whichcontained no UV-chromophores, using RP-HPLC with Indirect Photometric Detection,IPD. Pyridinium salts such as N-methylpyridinium iodide, N-methyl-2,2'-dipyridiniumiodide and N,N'-dimethyl-2,2'-dipyridinium diiodide, were used as the visualizationreagents, forming ion-pair complexes with the sulfonate surfactants. This allowedordinary UV-detection. N-methylpyridinium iodide proved to be a suitable reagent, bothwith respect to ease of preparation and response. The eluents consisted of mixtures ofacetonitrile and water, being 0.1 - 0.25 mM with respect to pyridinium salt. The methodwas sensitive and exhibited good signal to noise ratios, as well as linear responses over awide concentration range. All of the analyzed surfactants were separated, including thediastereomeric forms of some of the surfactants.
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