Determination of alkylphenols, alkylphenolethoxylates and linear alkylbenezenesulfonates in sediments by accelerated solvent extraction and supercritical fluid extraction

A method for the simultaneous extraction and determination of anionic surfactants in particular linear benzenesulfonates and non-ionic surfactants of the alkylphenolethoxylate-type and their degradation products, the alkylphenols, is presented. Extraction of anionic surfactants is achieved applying accelerated solvent extraction with pure methanol. For the complete extraction of the analytes the extraction pressure should be as low as possible (150 atm; 1 atm=101 325 Pa). Extraction of the alkylphenolethoxylates with recovery rates of 85% and 65% for nonylphenolethoxylate and octylphenolethoxylate, respectively, was accomplished by dynamic extraction using carbon dioxide modified with methanol. In this case, the extraction pressure should be as high as possible (greater than or equal to 450 atm). The combined method was tested with spiked and aged samples showing its perfect applicability for anionic surfactants. For non-ionic surfactants the extractability of aged samples is substantially reduced. Nevertheless surfactant concentrations in real samples can be quite well determined. (C) 1997 Elsevier Science B.V.