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Charlène Pouech Florent Lafay Laure Wiest Robert Baudot Didier Léonard Cécile Cren-Olivé 《Analytical and bioanalytical chemistry》2014,406(5):1493-1507
The use of polymer materials in industry for product packaging is increasing. The presence of additives in the polymer matrix enables the modification or improvement of the properties and performance of the polymer, but these industries are concerned regarding the extractability of these additives. The quantification of these additives is particularly challenging because of the presence of these substances as contaminants in all the analytical equipment and the diversity of their physicochemical properties. In this context, a multi-residue analytical method was developed for the trace analysis of the twenty main additives (and their degradation products) authorized in plastic products such as pharmaceutical packaging (e.g., antioxidants, release agents, and light absorbers). This analytical method consisted of a solid phase extraction (SPE) followed by an analysis using ultra-high performance liquid chromatography coupled to a tandem mass spectrometer (UHPLC-MS/MS). A comparison of two ionization interfaces and the optimization of the extraction procedure were discussed. The influence of the quality of the solvent type (distilled versus not distilled) and the nature of the SPE cartridges (Polypropylene versus Teflon®) were demonstrated. The optimized method exhibited a quantification limit lower than 20 ng mL?1 and recoveries between 70 % and 120 % for all compounds. Finally, the method was validated according to the ICH directive and was subsequently applied to the extraction of polymers under different pH conditions and storage temperatures. To the best of our knowledge, this study presents the first methodology allowing the simultaneous quantification of 24 additives at low ng mL?1. 相似文献
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Shao Z Rannou P Sadki S Fey N Lindsay DM Faul CF 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(44):12512-12521
The simple and elegant Buchwald-Hartwig cross-coupling reaction has been used to synthesise a designed range of new aniline-based tetramers in one step, and without the need for protecting groups. Variation of the central aromatic ring has provided the opportunity to carefully tune the optoelectronic properties in this series, thus enabling a structure-activity relationship study by using a range of photophysical and electrochemical techniques. As a result, the long-proposed sequences of electron-electron (EE) and electron-chemical (EC) processes that support the complex redox and proton-transfer reactions involved in the well-known switching of redox states of poly- and oligo(aniline)s are revealed here for the first time. We also present the initial results from time-dependent DFT calculations to clarify the optoelectronic behaviour of these oligomers. The dc-conductivity measurements of conducting thin films of this series, doped with the prototypical poly(aniline) protonating agent D,L-camphor-10-sulfonic acid (CSA), externally plasticised with triphenyl phosphate (TPP), and processed from m-cresol (MC) solutions, are also presented. 相似文献
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Jie Chen Wei Yan Esther J. Townsend Jiangtao Feng Long Pan Veronica DelAngelHernandez Charl F. J. Faul 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(34):11841-11845
Simple inorganic salts are used to tune N‐containing conjugated microporous polymers (CMPs) synthesized by Buchwald–Hartwig (BH) cross‐coupling reactions. Poly(triphenylamine), PTPA, initially shows a broad distribution of micropores, mesopores, and macropores. However, the addition of inorganic salts affects all porous network properties significantly: the pore size distribution is narrowed to the microporous range only, mimicking COFs and MOFs; the BET surface area is radically improved from 58 m2 g?1 to 1152 m2 g?1; and variations of the anion and cation sizes are used to fine‐tune the surface area of PTPA, with the surface area showing a gradual decrease with an increase in the ionic radius of salts. The effect of the salt on the physical properties of the polymer is attributed to adjusting and optimizing the Hansen solubility parameters (HSPs) of solvents for the growing polymer, and named the Beijing–Xi'an Jiaotong (BXJ) method. 相似文献
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Andrea Pizzi Haxel Lionel Ozores Martín Calvelo Rebeca García‐Fandio Manuel Amorín Nicola Demitri Giancarlo Terraneo Silvia Bracco Angiolina Comotti Piero Sozzani Charl X. Bezuidenhout Pierangelo Metrangolo Juan R. Granja 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(41):14614-14618
A cyclic hexapeptide with three pyridyl moieties connected to its backbone forms a hydrogen‐bonded dimer, which tightly encapsulates a single xenon atom, like a pearl in its shell. The dimer imprints its shape and symmetry to the captured xenon atom, as demonstrated by 129Xe NMR spectroscopy, single‐crystal X‐ray diffraction, and computational studies. The dimers self‐assemble hierarchically into tubular structures to form a porous supramolecular architecture, whose cavities are filled by small molecules and gases. 相似文献
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In this communication we report on the facile combination of hydrogen bonding and the ionic self-assembly (ISA) process to produce organized materials and fiber-containing organogel superstructures from functionalised oligoelectrolytic building blocks. 相似文献
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Dr. Emile R. Engel Dr. Abdelaziz Jouaiti Charl X. Bezuidenhout Prof. Mir Wais Hosseini Prof. Leonard J. Barbour 《Angewandte Chemie (International ed. in English)》2017,56(30):8874-8878
A non-interpenetrated metal–organic framework with a paddle-wheel secondary building unit has been activated by direct thermal evacuation, guest exchange with a volatile solvent, and supercritical CO2 drying. Conventional thermal activation yields a mixture of crystalline phases and some amorphous content. Exchange with a volatile solvent prior to vacuum activation produces a pure breathing phase with high sorption capacity, selectivity for CO2 over N2 and CH4, and substantial hysteresis. Supercritical drying can be used to access a guest-free open phase. Pressure-resolved differential scanning calorimetry was used to confirm and investigate a systematic loss of sorption capacity by the breathing phase as a function of successive cycles of sorption and desorption. A corresponding loss of sample integrity was not detectable by powder X-ray diffraction analysis. This may be an important factor to consider in cases where flexible MOFs are earmarked for industrial applications. 相似文献
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We propose two new tests for symmetry based on well-known characterisations of symmetric distributions. The performance of the new tests is evaluated and compared to that of other existing tests by means of a Monte Carlo study. All tests are carried out in a regression setup where we test whether the error distribution in a linear regression model is symmetric. It is found that the newly proposed tests perform favourably compared to the other tests. 相似文献
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Charl X. Bezuidenhout Dr. Vincent J. Smith Dr. Prashant M. Bhatt Prof. Catharine Esterhuysen Prof. Leonard J. Barbour 《Angewandte Chemie (International ed. in English)》2015,54(7):2079-2083
A systematic study is presented of three closely related microporous metal‐organic frameworks the pore dimensions of which vary according to the choice of 4,4′‐bipyridyl linker. The tunable linker allows exploration of the effect of increasing pore dimensions on the sorption behavior of the frameworks. The MOFs described capture CO2 under supercritical conditions and continue to sequester the gas under ambient conditions. Gas sorption isotherms for CO2 are compared with thermogravimetric data, and the CO2 molecules in the channels of the frameworks could be modeled using single‐crystal X‐ray diffraction analysis. Crystallographic data were used to construct a theoretical model based on DFT methods to calculate framework electrostatic potential maps with a view to understanding the nature of the sorbate–sorbent interactions. 相似文献