Multiwalled carbon nanotubes hollow microspheres were utilized as a fiber coating for the SPME of PAEs from tea beverages.

In this work, carbon nanotubes (CNTs) on silica rod (SiO₂) composite materials were prepared to extract six perfluorinated compounds (PFCs) in real environmental water samples by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The as-synthesized sorbents, hereafter referred to as CNT@SiO₂, were employed for dispersive solid-phase extraction (d-SPE). Perfluoroheptanoic acid (PFHpA), perfluorohexane sulfonate (PFHxS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorooctane sulfonate (PFOS), and perfluorodecanoic acid (PFDA) were selected as target analytes. The main extraction parameters were systematically optimized using the single-factor optimization method. The optimum adsorption parameters were as follows: adsorption time of 30 min, sorbent amount of 10 mg, pH 6 and NaCl concentration of 1.7 mol/L for sample solution, and 4 mL acetone as desorption solvent, desorption for 4 min. LC-triple quadrupole MS was conducted to quantify the selected PFCs in water samples. The mobile phase was 5 mmol/L ammonium acetate and methanol, the flow rate was set to 0.4 mL/min, the column temperature was set to 40 ℃, and the injection volume was 5.0 μL. The chromatographic separation system was equipped with a Kinetex C18 column (100 mm×2.1 mm, 1.7 μm). The mass spectrometer was operated with negative electrospray ionization in multi-reaction monitoring mode. CNT@SiO₂ was prepared in five batches and used as the d-SPE sorbent, and the relative standard deviations (RSDs) of the PFC recoveries among these five batches ranged from 4.9% to 9.3%. The reusability of the CNT@SiO₂ sorbent was assessed. After eight d-SPE cycles using the same sorbent, the RSDs of the PFC recoveries were 3.7%-8.2%. These results indicated that the sorbent had good stability and reusability for d-SPE. Excellent results were achieved under optimal extraction conditions. The method validation results indicated that the linear ranges were 0.4-1000 ng/L for PFNA, PFOS, and PFDA, 0.9-1000 ng/L for PFHpA, 0.7-1000 ng/L for PFHxS, and 0.6-1000 ng/L for PFOA. The correlation coefficients were 0.973-0.997. The limit of detection (LOD) and limit of quantification of the method were 0.10-0.26 ng/L and 0.33-0.87 ng/L, respectively. At 20 ng/L, the RSDs of the intra- and inter-day precisions were 2.73%-7.75% and 3.38%-8.21%, respectively. At 100 ng/L, the RSDs of the intra- and inter-day precisions were 2.95%-8.46% and 4.16%-9.14%, respectively. Finally, at 500 ng/L, the RSDs of the intra- and inter-day precisions were 2.51%-7.48% and 3.59%-9.63%, respectively. The developed method was applied to analyze six PFCs in tap water, barreled drinking water, and river water samples. PFOA and PFOS were determined in tap water at mass concentrations of 5.6 and 8.7 ng/L, respectively. No PFCs were found in barreled drinking water and river water. Satisfactory recoveries of 72.1%-109.6% at low, middle, and high spiking levels were also obtained. In conclusion, the d-SPE-LC-MS/MS method based on CNT@SiO₂ composite sorbents is accurate and sensitive. The results of this study demonstrate that CNT@SiO₂ is a good choice for the rapid and effective determination of PFCs from water samples. Further exploration of the use of CNT@SiO₂ sorbents for the extraction and determination of trace organic pollutions in environmental samples is in progress.

Two cationic porous organic polymer materials (CTN-POPs) were prepared via the Zincke reaction. CTN-POPs exhibited selective adsorption capabilities for carbon dioxide, dyes, and drugs in both gas and liquid phases.

Polychlorinated biphenyls （PCBs） pose serious threats to the environment and human health because they are among the most common and persistent organic pollutants globally. In this study， six PCBs were extracted from environmental water samples using multiwalled carbon nanotubes （MWCNTs） on polystyrene （PS） microspheres as the solid-phase microextraction （SPME） coating material for gas chromatography-tandem mass spectrometry （GC-MS/MS）. This coating material is highly stable and exhibited a high extraction efficiency. 2，2′，5，5′-Tetrachlorobiphenyl （PCB-52）， 2，2′，4，5，5′-pentachlorobiphenyl （PCB-101）， 2，3′，4， 4′，5-pentachlorobiphenyl （PCB-118）， 2，2′，3，4，4′，5′-hexachlorobiphenyl （PCB-138）， 2，2′，4，4′，5，5′-hexachlorobiphenyl （PCB-153） and 2，2′，3，4，4′，5，5′-heptachlorobiphenyl （PCB-180） were chosen as target analytes. The main extraction factors were optimized using a single-factor optimization method， which led to the following optimum extraction conditions： adsorption time， 50 min； agitation speed， 600 r/min； pH， 6； NaCl concentration， 1.5 mol/L； desorption temperature， 280 °C； and desorption time， 4 min. GC coupled with triple quadrupole mass spectrometry was used to quantify PCBs in water samples. The chromatographic separation system was equipped with a TG-5 SILMS column （30 m×0.25 mm×0.25 μm）， with electron impact ionization and multi-reaction monitoring modes used during mass spectrometry. Five batches of MWCNT@PS were used as SPME coating materials， which were determined to have relative standard deviations （RSD） of less than 8.8% for the six PCBs. The reusability of the MWCNT@PS coating was also investigated； RSD of the recoveries of 2.8%–9.3% were obtained after ten SPME cycles with the same coating. These results reveal that the MWCNT@PS coating materials are highly stable and reusable in SPME applications， with good results obtained under the optimal conditions. The established method exhibited linearity in the range of 0.03–1 000 ng/L for PCB-52 and PCB101， 0.07–1 000 ng/L for PCB118， PCB138， and PCB 153， and 0.10–1 000 ng/L for PCB-180， with correlation coefficients of 0.993-0.998. Limits of detection and quantification （LODs and LOQs， respectively） of 0.01–0.03 and 0.03–0.10 ng/L were determined for the developed method. The intra- and inter-day precisions exhibited RSDs of 1.64%–8.16% and 2.83%–8.41%， respectively， at 2 ng/L， 3.31%–7.19% and 3.79%–9.12%， respectively， at 10 ng/L， and 2.70%–9.38% and 4.04%–8.56%， respectively， at 100 ng/L. The established method was used to determine six PCBs in barreled drinking water， rainwater， and three environmental river water samples. No PCBs were found in barreled drinking water， rain water and river water. Satisfactory recoveries of 82.4%-113.2% were achieved at low， medium， and high levels. Accordingly， the MWCNT@PS-composite-coating-material-based SPME-GC-MS/MS method is accurate and effective. This study revealed that MWCNT@PS composites provide a good avenue for the rapid and sensitive detection of PCBs in water samples.