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Trihalomethanes (THMs) and halonitromethanes are the two most dominant categories of volatile disinfection by-products that pose considerable public health concerns. The pretreatment and determination methods of THMs in low concentrations, particularly trichloronitromethane (TCNM), have always been the focus of researchers. Metal-organic frameworks, which are effective adsorbents, have considerable potential for solid-phase microextraction (SPME) because of their tuned pore structure, large surface area, and high thermal and chemical stabilities. In this study, MIL-96 was successfully fabricated and developed as a coating fiber for SPME of THMs and TCNM in water samples. Several extraction parameters (i.e., extraction temperature, extraction time, stirring rate, pH, and ionic strength) and desorption parameters (i.e., temperature and time) were investigated and optimized in detail. Ionic strength, extraction temperature, and pH/desorption temperature were identified as key factors that affected the SPME efficiencies of THMs and TCNM. The developed method under optimal conditions obtained wide linearity (0.02–50 µg/L), low limits of detection (0.0030–0.0110 µg/L), and high enrichment factors (81–1181) for detecting THMs and TCNM. The spiked recoveries (1 and 10 µg/L) and relative standard deviations ranged from 81.0% to 109.9% and from 3.92% to 10.10%. Notably, the developed SPME method could overcome thermal degradation and showed excellent performance for TCNM. These results indicated the applicability of MIL-96 as coating fiber.

Magnetic N-doped carbon nanotubes were firstly applied as adsorbent in food analysis for pre-concentration of bisphenols in fruit juices followed by ultra-high performance liquid chromatography-tandem mass spectrometry determination. The magnetic nanoparticles were characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy and vibrating sample magnetometer. The adsorption conditions were further optimized by response surface methodology. Under optimal conditions, the method provided good linearity with correlation coefficient (r ≥ 0.9979), excellent intermediate precisions (2.71–5.91%, n = 3), low limits of detection (LODs) ranging from 0.43 to 2.47 ng L−1, and satisfying recoveries of three juice samples (between 90.6% and 101%).