Magnetic solid-phase extraction of hydrophobic analytes in environmental samples by a surface hydrophilic carbon-ferromagnetic nanocomposite

A new sorbent of carbon-ferromagnetic nanocomposite was proposed for the extraction of polycyclic aromatic hydrocarbons (PAHs) in environmental samples. The sorbent was specially designed with a hydrophobic sublayer and a hydrophilic surface, which endows the sorbent some unique features. The former shows high extraction capability for the PAHs and the latter provides benign compatibility with the sample matrix. The sorbent can be easily dispersed in aqueous solutions for extraction and no additional stirring or shaking was necessary to facilitate the dispersion, which may bring operational convenience especially for on-site sampling and extraction. Parameters affecting the extraction efficiency were investigated in detail. The optimal conditions were as follows: 10 mg of nanoparticles, 40 mmol/L of sodium chloride, 30 min of extraction time without shaking, hexane as the desorption solvent and 15 min as the desorption–sonication time. The results demonstrate that enrichment factors ranging from 35- to 133-fold were obtained for the analytes. The limits of detection and the limits of quantification are in the range of 0.015–0.335 ng/mL and 0.05–1.14 ng/mL, respectively. Finally, the new sorbent was successfully used for the extraction of PAHs in lake water samples.