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51.
Marián Masár Pavol Kruk Milan Luc Róbert Bodor Ladislav Danč Peter Troška 《Electrophoresis》2013,34(3):432-440
Adsorption processes on a PMMA chip linked with CZE separations of a group of 13 aliphatic and aromatic mono‐ and di‐amines were studied. Due to the lack of chromophores within aliphatic amines, contact conductivity detection implemented directly onto the chip was used for monitoring of cationic CZE separations. To prevent an adsorption of studied amines to the chip channels, the surface of PMMA chip was modified by dynamic coating. Different surface modifiers, such as aliphatic oligoamines (diethylenetriamine and triethylenetetramine), were added to the BGE solutions filling the chip channels. The effect of various concentrations of surface modifiers on peak profiles and separation parameters of amines was monitored. Of these, mainly, aliphatic di‐amines and aromatic mono‐amines adversely affected the CZE resolution of a whole group of analytes by their strong adsorption to the chip channels. A propionate BGE with pH 3.2 containing 100 μM triethylenetetramine and 25 mM 18‐crown‐6‐ether was found suitable for CZE resolution of 12 from a total of 13 amines studied. Simple dynamic modification of the surface of PMMA chip enabled fast (analysis time lasted 9 min), sensitive (sub‐μM LODs reached) and reproducible (1–3% RSD of the peak areas) CZE analysis of the aliphatic and aromatic amines. 相似文献
52.
Georgina Fortuny Laura Pineda Antoni Rúbies Francesc Centrich Ramon Companyó 《International journal of environmental analytical chemistry》2013,93(7):707-726
A method for determination of 61 organic pollutants (polycyclic aromatic hydrocarbons and organochlorine, organophosphorous and organonitrogen pesticides) is proposed. It is based on solid phase extraction (SPE) and subsequent analysis of the extract by liquid and gas chromatography coupled to tandem mass spectrometry. Method validation yielded to the following values: limits of quantification, from 0.005 to 0.020?µg?L?1; trueness, 95% to 113% and reproducibility (as percent relative standard deviation), 2% to 15%. Additionally, the method performed well in various proficiency tests. 相似文献
53.
Núria Mas Alessandro Agostini Dr. Laura Mondragón Dr. Andrea Bernardos Dr. Félix Sancenón Dr. M. Dolores Marcos Prof. Ramón Martínez‐Máñez Prof. Ana M. Costero Prof. Salvador Gil Prof. Matilde Merino‐Sanjuán Prof. Pedro Amorós Dr. Mar Orzáez Prof. Enrique Pérez‐Payá 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(4):1346-1356
The preparation of a new capped silica mesoporous material, Rh‐Azo‐S , for on‐command delivery applications in the presence of target enzymes is described. The material consists of nanometric mesoporous MCM‐41‐like supports loaded with Rhodamine B and capped with an azopyridine derivative. The material was designed to show “zero delivery” and to display a cargo release in the presence of reductases and esterases, which are usually present in the colon, mainly due to intestinal microflora. The opening and cargo release of Rh‐Azo‐S in vitro studies were assessed and seen to occur in the presence of these enzymes, whereas no delivery was noted in the presence of pepsine. Moreover, Rh‐Azo‐S nanoparticles were used to study controlled Rhodamine B dye delivery in intracellular media. HeLa cells were employed for testing the “non”‐toxicity of nanoparticles. Moreover, delivery of the dye in these cells, through internalization and enzyme‐mediated gate opening, was confirmed by confocal microscopy. Furthermore, the nanoparticles capped with the Azo group and loaded with a cytotoxic camptothecin ( CPT ) were also prepared (solid CPT‐Azo‐S ) and used as delivery nanodevices in HeLa cells. When this solid was employed, the cell viability decreased significantly due to internalization of the nanoparticles and delivery of the cytotoxic agent. 相似文献
54.
Headspace stir bar sorptive extraction followed by thermal desorption and gas chromatography with mass spectrometry to determine musk fragrances in sludge samples without sample pretreatment 总被引:1,自引:0,他引:1 下载免费PDF全文
Laura Vallecillos Marta Pedrouzo Eva Pocurull Francesc Borrull 《Journal of separation science》2014,37(11):1322-1329
A direct, simple and solvent‐free method based on headspace stir bar sorptive extraction and thermal desorption gas chromatography with mass spectroscopy was developed to determine 13 musk fragrances (six polycyclic musks, three nitro musks and four macrocyclic musks) in sludge without sample treatment. The optimal headspace stir bar sorptive extraction conditions were achieved when a polydimethylsiloxane stir bar was exposed for 45 min in the headspace of a 10 mL vial filled with 100 mg of sludge mixed with 0.2 mL of water stirred at 750 rpm at 80°C. The stir bar was then desorbed in the thermal desorption gas chromatography and mass spectrometry system, obtaining limits of detection between 5 and 30 ng/g. The method applicability was tested with sewage sludge from two urban wastewater treatment plants and from a potable water treatment plant. Results showed galaxolide and tonalide to be the most abundant musk fragrances found in wastewater treatment plants with maximal concentrations of 9240 and 7500 ng/g, respectively. Maximum concentration levels between 35 and 635 ng/g were found for musk ketone, musk moskene, traseolide, phantolide and celestolide in this kind of samples. Concentrations below the limits of quantitation of phantolide, galaxolide, tonalide and musk ketone were found in sludge from a potable water treatment plant. 相似文献
55.
Study of the retention behavior of iodinated X‐ray contrast agents in hydrophilic interaction liquid chromatography,comparing bare silica and zwitterionic stationary phases 下载免费PDF全文
Daniela Salas Francesc Borrull Rosa Maria Marcé Núria Fontanals 《Journal of separation science》2014,37(9-10):1111-1117
Iodinated X‐ray contrast media are the most widely used pharmaceuticals for intravascular administration in X‐ray diagnostic procedures. The increasing concern of the fate of these compounds into the environment has led to the development of analytical methods to determine them. However, these methods present problems due to the polar character of these analytes. In this paper, hydrophilic interaction LC is presented as an alternative technique. The retention of iodinated X‐ray contrast media was studied in two bare silica phases with different particle designs (i.e. porous and Fused Core?) and a zwitterionic sulfoalkylbetaine phase. The effect of the most important parameters of the mobile phase was studied for each stationary phase. It was observed that optimal mobile phase conditions included buffers with a high buffering capacity. Additionally, the retention mechanisms involved were studied in order to provide some insight into the possible occurring interactions. The contributions of partition and adsorption and the effect of the temperature on the retention of analytes were evaluated on all of the stationary phases. 相似文献
56.
Oleh Stetsiuk Abdelkrim El-Ghayoury Francesc Lloret Miguel Julve Narcis Avarvari 《Molecules (Basel, Switzerland)》2021,26(8)
Four new compounds of formulas [Cu(hfac)2(L)] (1), [Ni(hfac)2(L)] (2), [{Cu(hfac)2}2(µ-L)]·2CH3OH (3) and [{Ni(hfac)2}2(µ-L)]·2CH3CN (4) [Hhfac = hexafluoroacetylacetone and L = 3,6-bis(picolylamino)-1,2,4,5-tetrazine] have been prepared and their structures determined by X-ray diffraction on single crystals. Compounds 1 and 2 are isostructural mononuclear complexes where the metal ions [copper(II) (1) and nickel(II) (2)] are six-coordinated in distorted octahedral MN2O4 surroundings which are built by two bidentate hfac ligands plus another bidentate L molecule. This last ligand coordinates to the metal ions through the nitrogen atoms of the picolylamine fragment. Compounds 3 and 4 are centrosymmetric homodinuclear compounds where two bidentate hfac units are the bidentate capping ligands at each metal center and a bis-bidentate L molecule acts as a bridge. The values of the intramolecular metal···metal separation are 7.97 (3) and 7.82 Å (4). Static (dc) magnetic susceptibility measurements were carried out for polycrystalline samples 1–4 in the temperature range 1.9–300 K. Curie law behaviors were observed for 1 and 2, the downturn of χMT in the low temperature region for 2 being due to the zero-field splitting of the nickel(II) ion. Very weak [J = −0.247(2) cm−1] and relatively weak intramolecular antiferromagnetic interactions [J = −4.86(2) cm−1] occurred in 3 and 4, respectively (the spin Hamiltonian being defined as H = −JS1·S2). Simple symmetry considerations about the overlap between the magnetic orbitals across the extended bis-bidentate L bridge in 3 and 4 account for their magnetic properties. 相似文献
57.
58.
HOMO Stabilisation in π‐Extended Dibenzotetrathiafulvalene Derivatives for Their Application in Organic Field‐Effect Transistors 下载免费PDF全文
Dr. Yan Geng Dr. Raphael Pfattner Antonio Campos Prof. Wei Wang Dr. Olivier Jeannin Dr. Jürg Hauser Dr. Joaquim Puigdollers Prof. Stefan T. Bromley Prof. Silvio Decurtins Prof. Jaume Veciana Prof. Concepció Rovira Dr. Marta Mas‐Torrent Dr. Shi‐Xia Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(50):16672-16679
Three new organic semiconductors, in which either two methoxy units are directly linked to a dibenzotetrathiafulvalene (DB‐TTF) central core and a 2,1,3‐chalcogendiazole is fused on the one side, or four methoxy groups are linked to the DB‐TTF, have been synthesised as active materials for organic field‐effect transistors (OFETs). Their electrochemical behaviour, electronic absorption and fluorescence emission as well as photoinduced intramolecular charge transfer were studied. The electron‐withdrawing 2,1,3‐chalcogendiazole unit significantly affects the electronic properties of these semiconductors, lowering both the HOMO and LUMO energy levels and hence increasing the stability of the semiconducting material. The solution‐processed single‐crystal transistors exhibit high performance with a hole mobility up to 0.04 cm2 V?1 s?1 as well as good ambient stability. 相似文献
59.
Electrochemically Generated Nanoparticles of Halogen‐Bridged Mixed‐Valence Binuclear Metal Complex Chains 下载免费PDF全文
Emiliano Martínez‐Periñán Mohammad‐Reza Azani Dr. José M. Abad Dr. Eva Mateo‐Martí Dr. Félix Pariente Dr. Rubén Mas‐Ballesté Dr. Félix Zamora Prof. Encarnación Lorenzo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(23):7107-7115
Spherical nanoparticles composed of MMX chains can be made by a polymerization strategy driven by electrochemical processes. In particular, the [Pt2(MeCS2)4I2] (MMI2) dimetal subunit is employed as a monomer for the formation of [Pt2(MeCS2)4I]n spherical nanostructures on surfaces. We have paid particular attention to elucidating the general mechanism of the deposition process on the basis of in situ electrochemical measurements. The reduction of MMI2 to give the electrodeposition of nanostructures agrees well with formation of the reduced [MMI2]? species followed by a disproportionation mechanism mediated by iodide anions. The chemical composition of the particles was determined by energy‐dispersive X‐ray spectroscopy (EDX) and X‐ray photoelectron spectroscopy (XPS) to reveal the MMI2 polymer. 相似文献
60.
Dr. Albert Ferrer‐Ugalde Dr. Arántzazu González‐Campo Prof. Dr. Clara Viñas Dr. Jesús Rodríguez‐Romero Dr. Rosa Santillan Dr. Norberto Farfán Prof. Dr. Reijo Sillanpää Dr. Antonio Sousa‐Pedrares Dr. Rosario Núñez Prof. Dr. Francesc Teixidor 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(32):9940-9951
Two sets of o‐carborane derivatives incorporating fluorene and anthracene fragments as fluorophore groups have been successfully synthesized and characterized, and their photophysical properties studied. The first set, comprising fluorene‐containing carboranes 6 – 9 , was prepared by catalyzed hydrosilylation reactions of ethynylfluorene with appropriate carboranylsilanes. The compound 1‐[(9,9‐dioctyl‐fluorene‐2‐yl)ethynyl]carborane ( 11 ) was synthesized by the reaction of 9,9‐dioctyl‐2‐ethynylfluorene and decaborane (B10H14). Furthermore, reactions of the lithium salt of 11 with 1 equivalent of 4‐(chloromethyl)styrene or 9‐(chloromethyl)anthracene yielded compounds 12 and 13 . Members of the second set of derivatives, comprising anthracene‐containing carboranes, were synthesized by reactions of monolithium or dilithium salts of 1‐Me‐1,2‐C2B10H11, 1‐Ph‐1,2‐C2B10H11, and 1,2‐C2B10H12 with 1 or 2 equivalents of 9‐(chloromethyl)anthracene, respectively, to produce compounds 14 – 16 . In addition, 2 equivalents of the monolithium salts of 1‐Me‐1,2‐C2B10H11 (Me‐o‐carborane) and 1‐Ph‐1,2‐C2B10H11 (Ph‐o‐carborane) were reacted with 9,10‐bis(chloromethyl)anthracene to produce compounds 17 and 18 , respectively. Fluorene derivatives 6 – 9 exhibit moderate fluorescence quantum yields (32–44 %), whereas 11 – 13 , in which the fluorophore is bonded to the Ccluster (Cc), show very low emission intensity (6 %) or complete fluorescence quenching. The anthracenyl derivatives containing the Me‐o‐carborane moiety exhibit notably high fluorescence emissions, with ?F=82 and 94 %, whereas their Ph‐o‐carborane analogues are not fluorescent at all. For these compounds, we have observed a correlation between the Cc?Cc bond length and the fluorescence intensity in CH2Cl2 solution, comparable to that observed for previously reported styrene‐containing carboranes. Thus, our hypothesis is that for systems of this type the fluorescence may be tuned and even predicted by changing the substituent on the adjacent Cc. 相似文献