Qing Liu,Kevin Yan,Qiaomei Chen,Soumia Cheddah,Lin Shen,Han Xiao,Yan Wang,Chao Yan
Capillary column packed with silica colloidal crystals (SCC) exhibits great efficiency in liquid chromatography because of its highly-ordered structure and extremely narrow channels (about hundred nanometer in diameter) between the particles. However, problems arise due to the extremely high back-pressure created with its dense packings. It is also a challenge to prepare a stable SCC column with an appropriate length for chromatographic separation on a commercial instrument. We have synthesized monodispersed, sub-micron SiO 2 particles bonded with C18 functionality and fabricated SCC capillary columns up to 100 mm in length. The packing materials in the column displayed Bragg diffraction with blueish color under irradiation with white light, indicating the formation of SCC. The column performance was evaluated using pressurized capillary electrochromatography (pCEC) and column efficiencies of more than a hundred thousand plates per column (plate height < 1 μm) were achieved using peptide as a sample. The run-to-run reproducibility expressed with RSD in terms of retention time and peak area for aromatic compounds were less than 0.076% and 1.96%, respectively. These results demonstrate that the combination of pCEC and SCC columns may provide an innovative analytical technique with extraordinary efficiency, resolution and speed for the separation of complex samples.
Juan Zheng,Kun Wang,Erlun Luo,Dingcai Wu,Fang Zhu,Ruifen Jiang,Chengyong Su,Chaohai Wei,Gangfeng Ouyang
The monodisperse microporous carbon nanospheres (MMCNSs) were applied in solid phase microextraction for the first time. The MMCNSs-fiber was prepared by sol–gel technique and good repeatability and reproducibility were obtained, due to the excellent monodispersity of the MMCNSs . The sol–gel-MMCNSs fiber exhibited superior extraction ability for polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs), compared with the commercial polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber and the fiber prepared with its precursor, the monodisperse microporous polystyrene nanospheres (MMPNSs). Moreover, the fiber has good thermostability and strong acid/base durability. The sol–gel-MMCNSs fiber was then employed to detect PAHs and OCPs in aqueous samples by combining with gas chromatography–mass spectrometer (GC–MS). Under the optimized conditions, the detection limits of the proposed method ranged from 0.10 to 5.5 ng L −1 . Furthermore, the method was successfully utilized for the analysis of PAHs and OCPs in real samples, with satisfactory recoveries in the range of 81.0–120% for the Pearl River water samples and 72.8–118% for the coking wastewater samples.
Developing efficient and reliable adsorbents with simplified synthesis and mixed-mode performance is crucial for the accurate quantitative analysis of diverse coexisting environmental pollutants. A magnetic carboxylated hypercrosslinked organic polymer (Fe 3 O 4 /HCP-COOH) with reverse phase/cation exchange mixed-mode performance was synthesized through a two-stage process: (1) Fabrication of HCP-COOH via FeCl 3 -catalyzed Friedel-Crafts alkylation using 1,4-phenylenediacetic acid and 1,4-bis(chloromethyl)benzene; (2) In situ growth of Fe 3 O 4 nanoparticles on HCP-COOH through coprecipitation, utilizing FeCl₃ dually as polymerization catalyst and iron precursor to enhance process efficiency and waste minimization. The nanocomposite functioned as a mixed-mode sorbent for magnetic solid-phase extraction (MSPE), integrating dual retention mechanisms to selectively extract hydrophobic polycyclic aromatic hydrocarbons (PAHs) and cationic quaternary ammonium pesticides (QUATs), with subsequent analysis by GC-MS for PAHs and HPLC-MS/MS for QUATs respectively. Following optimization of adsorption pH, eluent composition, and contact time, the method exhibited high sensitivity with limits of detection (LODs) of 0.80-7.93 ng L⁻¹ for 15 PAHs and 0.02-16.31 ng L⁻¹ for 4 QUATs. Validation showed satisfactory recoveries of 89.5-98.3% (RSDs ≤11.2%) in snowmelt and 90.4-101.8% (RSDs ≤11.6%) in lake water (n=3), confirming practicality for simultaneous monitoring of hydrophobic and cationic contaminants in complex environmental water, offering significant advantages in multi-residue analysis for environmental monitoring applications.
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