Extraction of nonylphenol and nonylphenol ethoxylates from river sediments: Comparison of different extraction techniques

Five different extraction techniques (Soxhlet, automated Randall, accelerated solvent extraction, microwave-assisted solvent extraction and extraction with a surfactant solution) have been evaluated for the determination of nonylphenol (NP) and nonylphenol ethoxylates (NPEO) in river sediments. All the techniques were applied to the same three samples collected from northern Italian rivers. The analyses were performed with two RP columns, with different stationary reversed phases-a classical C-18 phase and a hexyl-phenyl phase. The recoveries and reproducibility of the different extraction techniques were comparable and all the methods gave reliable results. The variance of the results was dominated by the variance in sample homogeneity, sample preparation, and chromatographic analysis. A choice between the methods can be made on the basis of the cost and safety of each technique. Preliminary results obtained from use of a water-based extraction method with a surfactant solution (Tween-80), and its application to analysis of sediment and of worm tissue, are also presented.