Determination of anionic surface active agents using silica coated magnetite nanoparticles modified with cationic surfactant aggregates

• A sample preparation method was proposed for anionic surfactants determination.
• CTAB-coated nanomagnets allowed quantitative extraction of C10–C13 LAS homologues.
• Excellent extractability was achieved with reduced amounts of CTAB and nanoparticles.
• The proposed method was applicable to the analysis of natural aqueous matrices.

The development of a novel methodology for extraction and preconcentration of the most commonly used anionic surface active agents (SAAs), linear alkylbenzene sulfonates (LAS), is presented herein. The present method, based on the use of silica–magnetite nanoparticles modified with cationic surfactant aggregates, was developed for determination of C10–C13 LAS homologues. The proposed methodology allowed quantitative recoveries of C10–C13 LAS homologues by using a reduced amount of magnetic nanoparticles. Limits of detection were in the range 0.8–1.9 μg L−1 for C10–C13 LAS homologues, while the repeatability, expressed as relative standard deviation (RSD), ranged from 2.0 to 3.9% (N = 6). Finally, the proposed method was successfully applied to the analysis of a variety of natural water samples.