RESUMEN
Anionic surfactants in waters were determined using on-line double microporous membrane extraction-flow injection analysis method. This method was based on the extraction of the ion-association complex (λ_(max)=650 nm) which formed from methylene blue cation and anionic surfactants. The on-line double microporous membrane liquid-liquid extraction phase separators were adopted. Optimization of variables of the flow injection manifold, groove mechanical dimension of the phase separator, and pore size of the membrane was performed. The proposed method had a linear range of 25.0-1000.0 μg/L(r≥0.999). The detection limit was 4.28 μg/L. The relative standard deviation(n=7) of different concentration was 0.7%-6.0%. The recovery was between 96%-110% and the sample throughput was 18 h-1. The method was applied to the analysis of standard Reference materials with satisfactory results. For practical application, two water samples were analyzed with the established method.