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A time-saving method was applied to synthesize methyltrimethoxy-modified magnetic mesoporous silica with or without p-toluenesulfonic acid as the catalyst for magnetic solid-phase extraction. The synthesized materials were systematically characterized. Results demonstrated that methyltrimethoxy modified magnetic mesoporous silica with p-toluenesulfonic acid as the catalyst has a relatively smaller aperture and extreme hydrophobicity (water contact angle of 135°). To evaluate the feasibility of these prepared materials as effective adsorbents, it was combined with gas chromatography and electron capture detection to determine 26 polychlorinated biphenyls in environmental water. The result revealed that methyltrimethoxy modified magnetic mesoporous silica with p-toluenesulfonic acid as the catalyst had the best extraction efficiency and recovery. Under the optimized extracted conditions, the proposed method showed good linearity within the concentration range of 5 to 200 ng/L with correlation coefficients of 0.9969 to 0.9999. The limits of detection and quantification based on signal-to-noise ratios of 3 and 10 were in the range of 0.16 to 0.91 and 0.52 to 3.0 ng/L, respectively. The polychlorinated biphenyl concentrations in environmental water samples were successfully determined using the developed method. PCB008 and PCB110 were 4.05 and 8.52 ng/L in Red-Star lake water (Hubei Province, China), respectively.

Alkyl moieties which can retain target analytes due to their lipophilicity are important in sample preparation. In this work, hexadecyl-functionalized magnetic core-shell microspheres (FeO@SiO-C) was successfully prepared by one-pot sol-gel method and used for magnetic solid-phase extraction of polychlorinated biphenyls (PCBs) in environmental water samples. Optimized preparation method was achieved by altering the adding moment of hexadecyl-silane. The resultant materials were systematically characterized by scanning electron microscope, transmission electron microscope, Fourier transform infrared spectroscopy, energy dispersive X-ray spectrometry, tensionmeter, and vibrating sample magnetometer. The results demonstrated that the optimized adsorbent exhibited core-shell structure, superparamagnetic (66 emu/g), and extremely hydrophobic (water contact angle of 122°) properties. To evaluate the extraction performance, the prepared material coupled with gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) was applied to determinate PCBs. The extraction conditions were optimized. Under the optimal conditions, the proposed method showed a good linearity range of 1-100 ng L with correlation coefficients (R) of 0.9989-0.9993. Based on a signal-to-noise ratio of 3 and 10, the limits of detection (LODs) and limits of quantification (LOQs) were in the range 0.14-0.27 and 0.39-0.91 ng L, respectively. The intra- and inter-day relative standard deviations (RSDs) were less than 9.06%. The absolute recoveries of PCBs in spiked real water samples were in the range of 75.17 to 101.20%. Additionally, reusability and batch-to-batch reproducibility of the resultant material were acceptable with RSDs less than 5.64 and 3.25%, respectively. Graphical Abstract The synthesis procedure of FeO@SiO-C and determination of PCBs in water sample 129 × 50 mm (300 × 300 DPI).

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