n-Octadecylphosphonic acid grafted mesoporous magnetic nanoparticle: Preparation, characterization, and application in magnetic solid-phase extraction.

A new sorbent for magnetic solid-phase extraction, n-octadecylphosphonic acid modified mesoporous magnetic nano particles (OPA/MMNPs), was easily prepared via a two-step strategy. MMNPs were synthesized by a solvent-thermal process, and then OPA was grafted onto the surface of MMNPs via the strong Lewis acid/base interaction. The resultant material was characterized by transmission electron microscopy, tensionmeter, Fourier-transform infrared spectroscopy, vibrating sample magnetometry, elemental analysis, and nitrogen adsorption analysis. The results demonstrated that the particles exhibited mesoporous structure, superparamagnetic (57emu/g) and extremely hydrophobic (water contact angle of 136°) properties. To evaluate the extraction performance of the resultant sorbent, polycyclic aromatic hydrocarbons (PAHs) were chosen as model analytes. The extraction conditions were optimized. Based on these, a rapid, convenient and efficient method for the determination of PAHs in water samples was established by combination of magnetic solid-phase extraction and gas chromatography-mass spectroscopy. The linearity range of proposed method was 0.2-100μg/L with correlation coefficients (R(2)) of 0.9726-0.9970. The intra- and inter-day relative standard deviations (RSDs) were less than 17.6%. Batch-to-batch reproducibility was acceptable with RSD values less than 12.1%.