Flower-like calix[6]arene-based covalent organic framework for membrane extraction of sulfonamides in animal-derived food through host-guest interaction prior to determination with ultra-high performance liquid chromatography-tandem mass spectrometry.

Supramolecular macrocycle-based covalent organic frameworks (COFs) are promising adsorbents for adsorption of hazards due to their host-guest recognition property. However, most supramolecular macrocycles are conformationally flexible, making them challenging to introduce into COFs. In this work, a calix[6]arene-based COF (CX6-BD COF) was fabricated with a unique flower-like morphology and high crystallinity. Especially, the cavity of CX6 exhibited host-guest inclusion interaction for sulfonamides (SAs), which was verified by quantum chemistry calculation. The integration of the porosity of COFs with the recognition cavity of CX6 made CX6-BD COF display excellent enrichment performance for SAs, with good enrichment factors (EFs) between 77 and 96. The material was employed as an adsorbent for COF membrane filter extraction, coupled with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) to simultaneously enrich and determine seven SAs in animal-derived food. The analytical method showed a wide linear range (0.01-100 µg/L and 0.05-100 µg/L) and low detection limits (3-10 ng/L). The established method was successfully applied to sensitively determine SAs in chicken, pork and beef samples, which achieved satisfactory recoveries (73.8-113%). These results demonstrated CX6-BD COF has good application potential in determination of trace and ultra-trace SAs in complex food matrices as an adsorbent.

Calix[4]arene-based covalent organic frameworks with host-guest recognition for selective adsorption of six per- and polyfluoroalkyl substances in food followed by UHPLC-MS/MS detection.

Long-term ingestion or exposure to food contaminated with per- and polyfluoroalkyl substances (PFASs) may cause potential harm to human health. Due to the low contents of PFASs in complex food matrices, it is of great significance to develop adsorbents with excellent properties to enrich PFASs before analysis. Herein, calix[4]arene (CX4) was used as building block to prepare ordered crystalline covalent organic frameworks (COFs). The perfect combination of the host-guest recognition ability of CX4 and the porosity of COFs makes the CX4-COFs selective and high adsorption capacity for linear molecular PFASs (261-1055 mg/g). The adsorption behavior and mechanism were verified by isotherm adsorption experiments and simulation calculations. The CX4-COFs were then used as adsorbents for membrane solid-phase extraction (M-SPE), combined with ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) to determine PFASs in food. The method has low detection limits (0.11-0.28 ng/kg) and good precision (1.3%-9.8%), and has been successfully applied to the simultaneous enrichment and determination of six PFASs in fish, shrimp and shellfish. Satisfactory recoveries (79.9%-118%) were obtained. This study provides a new strategy for preparing CX4-COFs containing macrocyclic molecules with different morphologies and expands the application of COFs as attractive enrichment media for sample pretreatment.

One-pot synthesis of pillar[5]quinone-amine polymer coated silica as stationary phase for high-performance liquid chromatography.

To expand the application of pillararene in chromatographic separation, we designed and fabricated a pillar[5]quinone-amine polymer coated silica through quinone-amine reaction by facile one-pot synthesis method, which was applied as a stationary phase for high-performance liquid chromatography. Separation of hydrophobic compounds, hydrophilic compounds, halogenated aromatic compounds, and 11 aromatic positional isomers was achieved successfully in this stationary phase. Reverse-phase separation mode and hydrophilic-interaction separation mode were proved to exist, indicating the potential application of the mix-mode stationary phase. Studies of chromatographic retention behavior and molecular simulation showed that multiple interactions might play an important role in the separation process, including hydrophobic interaction, hydrogen-bonding interaction, aromatic π-π interaction, electron donor-acceptor interaction, and host-guest interaction. Column repeatability and stability were tested, which showed relative standard deviations of retention time less than 0.2% for continuous 11 injections, and the durability relative standard deviations of retention time were less than 0.91% after 90 days. This novel design strategy would broaden the application of pillararene-based covalent organic polymer in chromatography and separation science.

Robotic mobile and mirror milling of large-scale complex structures.

Robotization, miniaturization and portability have become the new development trend of milling equipment for large-scale complex structures, and the robotic mobile and mirror milling technology has reached remarkable progress in practical production.

Effective enrichment and detection of bisphenol diglycidyl ether, novolac glycerol ether and their derivatives in canned food using a novel magnetic sulfonatocalix[6]arene covalent cross-linked polymer as the adsorbent.

A core-shell magnetic sulfonatocalix[6]arene covalently cross-linked polymer was proposed as a magnetic adsorbent, combined with ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) for the enrichment and determination of epoxy derivatives in canned foods. The adsorbent has high density of host-guest recognition functional groups, abundant binding sites and suitable cavity size, showing good extraction performance for epoxy derivatives. Quantum chemical simulation calculations provedmultiple interaction forces in the adsorption process. Theextractionparameterswere investigated. Under optimized experimental conditions, 13 kinds of target analytes showed low detection limits (0.0072-0.023 ng/g) and good precisions (RSDs of 0.8 %-9.4 %). This method has been successfully applied to the simultaneous determination of 13 kinds of epoxy derivatives in different food samples including canned beverage, fish, meat, and milk powder. Satisfactory recoveries (74.9 %-118 %) were obtained. The results showed the potential application prospects in the enrichment and detection of hazardous substances in food.

Research progress on sample pretreatment methods for migrating substances from food contact materials.

Excessive absorption of migrating substances from food contact materials can affect human health. Thus, it is essential to analyze the migration of contaminant from food contact materials. However, comprehensive analysis has been challenged by low concentration of migrating substances, manifold and complex matrix interference of food contact materials. Therefore, appropriate sample pretreatment methods should be applied before instrumental detection, which is essential to improve the analytical efficiency, sensitivity, and reliability. This paper systematically reviews the development of sample pretreatment methods for analysis of migrating substances from food contact materials in the past decade. To extract volatile and semi-volatile substances, headspace extraction, headspace solid phase microextraction, and purge and trap technique are discussed. For non-volatile substances, solid-liquid extraction and field-assisted extraction are usually used to extract them from food contact materials, while liquid-liquid extraction, solid phase extraction, and their corresponding microextraction techniques play important roles on enrichment process. In addition, new progress in developments of sample pretreatment methods of food contact materials is summarized, covering new devices, specific adsorbents, and sample preparation methods for rapid detection. An outlook of future prospect of sample pretreatment, especially for non-targeted analysis of non-intentionally added substances is briefly discussed.

Effective preparation of magnetic molecularly imprinted polymer nanoparticle for the rapid and selective extraction of cyfluthrin from honeysuckle.

Cyfluthrin is a widely used pesticide. In this study, a sensitive and efficient magnetic molecularly imprinted polymer (MMIP) was prepared by surface molecular imprinting, which used functionalized Fe3O4 particles as magnetic cores. Cyfluthrin was extracted and enriched using magnetic molecularly polymer for analyzing pesticide residue of Chinese herbal medicines. The crystal type, microstructure, particle size, saturation magnetization, and characteristic functional groups of the synthesized MMIPs were analyzed by analysis equipment. The results of isothermal adsorption and kinetic adsorption indicated that MMIPs reached adsorption equilibrium at 30 min, with a maximum capacity of 4.9 mg g-1, which had good adsorption performance, while selective adsorption experiments showed that MMIPs had higher affinity for cyfluthrin. Under the optimized conditions, the limit of detection (LOD) and the limit of quantification (LOQ) were 32.987 ng ml-1 and 109.955 ng ml-1, respectively. And linear range (30-3000ng ml-1) of cyfluthrin with correlation coefficient R2=0.9979, and MMIPs were used in honeysuckle, the recoveries were 91.5%∼97.2%, and RSD was 5.35%∼8.32% (n = 3). It is indicated that the magnetic molecularly imprinted polymer can be used as an effective material for the specific separation of cyfluthrin from honeysuckle.

Magnetic molecularly imprinted polymer combined with high performance liquid chromatography for selective extraction and determination of the metabolic content of quercetin in rat plasma.

In this study, a novel magnetic solid phase extraction adsorbent was prepared, namely Fe3O4@SiO2 as the carrier, quercetin as the template molecule, acrylamide (AM) as the functional monomer, ethylene glycol dimethacrylamide (EGDMA) as the crosslinker, 2,2'-azobisisobutyronitrile (AIBN) as the initiator to prepare magnetic molecularly imprinted polymer (MMIPs) with specific adsorption of quercetin by surface molecular imprinting technique. MMIPs were characterized by Fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD) and transmission electron microscope (TEM). The binding properties of MMIPs were evaluated by isothermal adsorption, kinetic adsorption and selective adsorption experiments. The results showed that the saturated adsorption capacity and adsorption time were 17.9 µmol/g and 20 min, respectively, and showed high selectivity for quercetin. Under optimized conditions, the limit of detection (LOD) and limit of quantitation (LOQ) were 55.327 ng/mL and 184.413 ng/mL, respectively. The recovery and RSD were 85.34-95.67% and 3.36-6.59, respectively. We successfully combined magnetic solid phase extraction with high performance liquid chromatography (MSPE-HPLC-UV) for the enrichment, separation and detection of quercetin in rat plasma. The results showed that the peak and half-life of quercetin in plasma were 1.5 h (32.310 µg/mL) and 3 h, respectively. The method was simple, rapid and efficient, and could be applied to the separation and detection of quercetin in complex matrices, and also provides a basis for the separation and identification of other natural chemical components.

A missense mutation (G604S) in the S5/pore region of HERG causes long QT syndrome in a Chinese family with a high incidence of sudden unexpected death.

Long QT syndrome (LQTS) is characterized by abnormalities in cardiac repolarization that lead to prolongation of the electrocardiographic (ECG) QT interval. Mutations in the human ether-a-go-go-related gene (HERG, KCNH2) cause the chromosome 7-linked LQT2 form of congenital LQTS, which is characterized by a prolonged QT interval and a bifid T-wave with an increased susceptibility to life-threatening cardiac arrhythmias, especially in children. We describe the genotypic and phenotypic pedigree of a large Chinese family (n = 36) in which 11 members were diagnosed with LQTS on the basis of typical ECG patterns for LQT2. Symptomatic syncopal episodes appeared in seven members of this family at a young age; an additional four members had died suddenly at ages of 18, 19, 24 and 70 years, respectively. Screening for SCN5A and HERG candidate genes identified a heterozygous missense mutation 1810G-->A in exon 7 of HERG that leads to the substitution of the amino acid glycine by serine (G604S); this mutation was located in the S5/pore region of the HERG protein and was associated with a malignant phenotype. Ten of the family members carrying the mutation showed a prolongation of the corrected QT interval (QTc), and seven of these had experienced multiple syncopal episodes. The retrospective examination of documented ECG records revealed that one family member who had died suddenly also had a prolonged QT interval. This study is the first to demonstrate a close correlation between clinical phenotype and genotype with a 100% penetrance based on the pedigree of a Chinese family with LQT2.