Analytical procedures for the determination of surfactants in environmental samples

Because of their specific physical and chemical properties (amphiphilicity, solubility in polar and nonpolar liquids, ability to form micelles, adsorption at phase boundaries, low toxicity) surfactants (surface-active compounds) are widely applied in industry and in the household. As their applications are on a very large scale, it has become necessary to acquire a more detailed understanding of their environmental fate. In the methodologies for analysing environmental samples, the isolation and/or preconcentration of analytes constitutes an important step. The usual techniques are liquid-liquid extraction (LLE), solid-phase extraction (SPE - also used for extract clean-up contains following analytes isolated by another technique) or accelerated solvent extraction (ASE). For the analysis of samples/extracts, depending on whether information is required - the total concentration or the levels of particular surface-active compounds in environmental samples - spectrophotometry, tensammetry or electrophoresis, and chromatography may be used. Nowadays, high-performance liquid chromatography (HPLC) is usually coupled with a universal mass spectrometry detector (MS) (or tandem mass spectrometry detector MS-MS), what allows for detection, identification and quantification the various compounds in a particular group of surfactants in suitably prepared solvent extracts.