Facile preparation of raisin-bread sandwich-structured magnetic graphene/mesoporous silica composites with C18-modified pore-walls for efficient enrichment of phthalates in environmental water

• Develop raisin-bread sandwich-structured graphene/mesoporous silica composites.
• Prepare magnetic graphene@mesoporous SiO2 with C18-modified interior pore-walls.
• Apply mag-graphene@mSiO2-C18 as SPE sorbents for enrichment of phthalates in water.
• Investigate the anti-interference ability of adsorbents to macromolecular proteins.
• Determine phthalates successfully from tap water sample using the proposed method.

In this study, novel raisin-bread sandwich-structured magnetic graphene/mesoporous silica composites with C18-modified interior pore-walls (mag-graphene@mSiO2-C18) were synthesized by coating mesoporous silica layers onto each side of magnetic graphene through a surfactant-mediated co-condensation sol–gel process. The prepared functionalized nanocomposites possessed marvelous properties of extended plate-like morphology, fine water dispersibility, high magnetic response, large surface area (315.4 cm2 g-1), uniform pore size (3.3 nm) and C18-modified interior pore-walls. Several kinds of phthalates were selected as model analytes to systematically evaluate the performance of adsorbents in extracting hydrophobic molecules followed by gas chromatography–mass spectrometry analyses. Various extraction parameters, including pH value of sample solution, amounts of adsorbents, adsorption time, species and volume of eluting solvent, and desorption time were optimized. The anti-interference ability to macromolecular proteins was also investigated. Method validations such as linearity, recovery, reproducibility, and limit of detection were also studied. Finally, mag-graphene@mSiO2-C18 composites were successfully applied to analyzing phthalates in environmental water samples. The results indicated that this novel approach offered an attractive alternative for rapid, convenient, efficient and selective magnetic solid-phase extraction for targeted hydrophobic compounds.