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121.
Study of alloxydim photodegradation in the presence of natural substances: Elucidation of transformation products 总被引:1,自引:0,他引:1
Beatriz Sevilla-Morn Pilar Sandín-Espaa M. Jesús Vicente-Arana Jos L. Alonso-Prados Jos M. García-Baudín 《Journal of photochemistry and photobiology. A, Chemistry》2008,198(2-3):162-168
A photodegradation study of alloxydim was performed under simulate solar irradiation (Suntest apparatus) at different irradiation intensities. Moreover, indirect photolysis of the tested herbicide was investigated under the presence of various concentrations of humic acids (HA), nitrate and Fe (III) ions. The photodegradation of alloxydim follows a first-order reaction kinetics in all cases. HA inhibited the photolysis kinetic whereas rate constants measured in the presence of nitrate ions indicated no effect on degradation. On the contrary, Fe (III) ions enhanced the photodegradation rate of alloxydim. Kinetics experiments were monitored by HPLC–DAD and the half-lives ranged from 165.78 to 4.63 min for different intensities in direct photolysis and from 104.81 to 1.14 min for indirect photolysis. The study of transformation products have been investigated by HPLC coupled to quadrupole time-of-flight mass spectrometry (QTOF-MS) employing the electrospray technique.The most important transformation process was found to be the cleavage of the O–N bond of the oxime moiety. Minor photo-isomerization to Z-isomer was also observed. The appearance of these degradation products is reported in aqueous media for the first time. 相似文献
122.
The crystal structures of compounds Na[Cr(dipic)2] · 2H2O (1) and [Cr(dipic)(phen)Cl] · 1/2H2O (2), dipic = dipicolinate, phen = 1,10-phenantroline, were determined. In both complexes, Cr(III) is in a distorted octahedral environment. In complex (1), the metal is coordinated to two nearly perpendicular dipic anions acting as tridentate ligands through one oxygen of each carboxylate group and the pyridinic nitrogen atom. In complex (2), Cr(III) ion is similarly coordinated to a dipic anion, defining a ligand equatorial plane. The phen molecule bridges the remaining equatorial coordination site and one of the axial positions through its N-atoms. The other axial position is occupied by a chloride ion. 相似文献
123.
Aline Klassen Manuela Leticia Kim Mabel Beatriz Tudino Nivaldo Baccan Marco Aurélio Zezzi Arruda 《Spectrochimica Acta Part B: Atomic Spectroscopy》2008
A flow injection hydride generation system with a metal furnace atomizer (Inconel 600® alloy) was employed for Bi and Se determination. The presented methods have linear ranges up to 200 and 500 μg L− 1 for Bi and Se, respectively, with good linearities (r2 = 0.9997 and 0.9974, respectively). The limits of quantification obtained according to IUPAC recommendations were 2.3 μg L− 1 for Bi and 6 μg L− 1 for Se, and the relative standard deviations (N = 6) based on Bi and Se analytical responses from real samples were 2.7% and 10%, respectively. Accuracy evaluations were based on certified materials such as SRM 361, SRM 363, and SRM 364 (steel alloys) for Bi, Mess-3 (marine sediment), SRM 397 (human hair), and Bio-Rad2 — 69042 (urine) for Se. Good agreements between the results were obtained at the 95% confidence level, according to the t-test. 相似文献
124.
Juárez BH Meyns M Chanaewa A Cai Y Klinke C Weller H 《Journal of the American Chemical Society》2008,130(46):15282-15284
Insights to the mechanism of CdSe nanoparticle attachment to carbon nanotubes following the hot injection method are discussed. It was observed that the presence of water improves the nanotube coverage while Cl containing media are responsible for the shape transformation of the nanoparticles and further attachment to the carbon lattice. The experiments also show that the mechanism taking place involves the right balance of several factors, namely, low passivated nanoparticle surface, particles with well-defined crystallographic facets, and interaction with an organics-free sp2 carbon lattice. Furthermore, this procedure can be extended to cover graphene by quantum dots. 相似文献
125.
Basic Physicochemical Properties of Polyethylene Glycol Coated Gold Nanoparticles that Determine Their Interaction with Cells
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Dr. Pablo del Pino Fang Yang Dr. Beatriz Pelaz Dr. Qian Zhang Karsten Kantner Raimo Hartmann Dr. Natalia Martinez de Baroja Marta Gallego Marco Möller Dr. Bella B. Manshian Dr. Stefaan J. Soenen René Riedel Prof. Dr. Norbert Hampp Prof. Dr. Wolfgang J. Parak 《Angewandte Chemie (International ed. in English)》2016,55(18):5483-5487
A homologous nanoparticle library was synthesized in which gold nanoparticles were coated with polyethylene glycol, whereby the diameter of the gold cores, as well as the thickness of the shell of polyethylene glycol, was varied. Basic physicochemical parameters of this two‐dimensional nanoparticle library, such as size, ζ‐potential, hydrophilicity, elasticity, and catalytic activity ,were determined. Cell uptake of selected nanoparticles with equal size yet varying thickness of the polymer shell and their effect on basic structural and functional cell parameters was determined. Data indicates that thinner, more hydrophilic coatings, combined with the partial functionalization with quaternary ammonium cations, result in a more efficient uptake, which relates to significant effects on structural and functional cell parameters. 相似文献
126.
García-Acosta B García F García JM Martínez-Mañez R Sancenón F San-José N Soto J 《Organic letters》2007,9(13):2429-2432
Polymeric films containing pyrylium derivatives showing a selective color modulation from yellow to red in the presence of the poorly coordinating hydrogen carbonate anion in water at neutral pH have been developed. 相似文献
127.
Ito FM Petroni JM de Lima DP Beatriz A Marques MR de Moraes MO Costa-Lotufo LV Montenegro RC Magalhães HI Pessoa Cdo O 《Molecules (Basel, Switzerland)》2007,12(2):271-282
Part of our research program concentrates on the discovery of new bioactive compounds prepared either by total synthesis or molecular transformation of compounds with bioactivity profiles. In this work we have focused our interest on chemical transformations of the Diels-Alder adduct tricyclo[6.2.1.0(2,7)]undeca-4,9-dien-3,6-dione in order to obtain cage-like compounds and derivatives, followed by an evaluation of their biological activity. 相似文献
128.
Lolo M Pedreira S Vázquez BI Franco CM Cepeda A Fente CA 《Analytical and bioanalytical chemistry》2007,387(5):1933-1937
An efficiency extraction of fluoroquinolones in chicken muscle was achieved by pulverizing it in a freezer mill before treatment
with NaOH (10mM)/MeCN (1:1). The improvement of cryogenic grinding in the extraction was demonstrated for the same piece (whole
leg) of four chickens treated with enrofloxacin in equal doses. A confirmatory method based on high-performance liquid chromatography
tandem mass spectrometry (HPLC-MS/MS) was used to analyze the extracts. The chromatographic separation was achieved in 5min
with a Synergi Fusion-RP 80A (50 x 2mm, 4μm) column filled with a hybrid polymer. The HPLC was coupled with a detector based
in a quadrupole–linear ion trap Q-TRAP that allows a confirmatory detection according to the European legislation. The specificity
of the method was assessed by testing a number of representative blank muscle samples (n = 10) to verify the absence of potential interfering compounds. The limits of detection and quantitation were 2 and 5ng g-1 of quinolones in muscle samples, respectively. The chromatographic method was demonstrated to be linear for the range studied
(5–500ng g-1) with the P value for lack-of-fit in the ANOVA table greater or equal to 0.10 (calibration coefficient 0.9998 and 0.9996 for ciprofloxacin
and enrofloxacin, respectively). The mean intra-day relative standard deviation (RSD) (n = 6, c = 50ng g-1) was 6%; inter-day assay gave a RSD of 12%. The extraction and clean-up were carried out in one step with very satisfactory
recovery data (between 65 and 101%). 相似文献
129.
A simple, expeditious procedure for confirming the presence of N-nitrosamines in previously screened positive water samples was proposed. Water samples were continuously aspirated into a photometric flow system for screening. Positive samples were then confirmed and N-nitrosamines were identified by gas chromatography using different detectors (mass spectrometry, flame ionization and nitrogen-phosphorus). The system for the screening purpose was based on the preconcentration of the analytes onto a sorbent column, elution, and derivatization to form nitrite, then formation of a coloured product (Griess reaction) and photometric detection. The detection limits of the gas chromatographic method for 100 ml of sample were 2.0-3.5 microg/l, 20-80 and 3-13 ng/l for flame ionization, nitrogen-phosphorus and mass spectrometric detectors, respectively. The precision as RSD was similar for all detectors (3.0-6.5%). The screening of different types of water showed that wastewaters contain levels of N-nitrosamines that can be detected only using MS as a detector. 相似文献
130.
Neumann MG Schmitt CC Prieto KR Goi BE 《Journal of colloid and interface science》2007,315(2):810-813
A method based on the aggregate to monomol emission ratio, I(aggr)/I(monomol), was used to determine the minimal hydrotropic concentration (MHC) of aromatic hydrotropes. The main advantage of this method is that it does not require the use of probes or other additives, which might disrupt the aggregation process. Also, it relies on spectrophotometric measurements, which are more sensitive and less arduous than others, like conductivity, light scattering and surface tension. 相似文献