Search results for "Ethylene"

Direct determination of oleic acid in soybean oil by capacitively coupled contactless conductivity detection capillary electrophoresis in an oil-misc…

2014

Este trabalho teve por objetivo desenvolver um método analítico direto e rápido para a determinação de ácido oleico em óleo de soja por eletroforese capilar com detecção condutométrica sem contato. O eletrólito de corrida empregado foi uma mistura metanol/1-propanol (1:6 v/v) contendo 4 × 10-2 mol L-1 de KOH e 10% (v/v) em etileno glicol. As amostras foram preparadas pela solubilização de 50 g L-1 de óleo de soja e 1,33 × 10-3 de ácido salicílico (padrão interno) no eletrólito de corrida. Os ensaios quantitativos foram realizados adicionando ácido oleico puro às amostras, na faixa entre 0,53 e 2,13 × 10-3 mol L-1. Sob polaridade negativa, os solutos aniônicos deslocaram-se mais rapidamente …

ChemInform Abstract: Diels-Alder Reactions of in situ Generated N-Benzoylindolo-2,3- quinodimethane with Carbodienophiles.

2010

The indolo-2,3-quinodimethane (5), generated from 2,3-bis(bromomethyl)indole (4), was trapped with unsymmetrical carbodienophiles or N, N′-p-phenylenedimaleimide to furnish the 1,2,3,4-tetrahydrocarbazoles (6–9). [4 + 2]-Cycloaddition of 5 with tetracyanoethylene gave rise to the tetracyanocarbazole (10) and a subsequent product 11a or 11b. The Diels-Alder reaction of 5 with divinyl sulfone was regiospecific within the detection limits of HPLC analysis. Similarly, the reaction of 5 with N, N′-p-phenylenedimaleimide yielded solely the stereoisomer 9.

Development of an ICP-IDMS method for accurate routine analyses of toxic heavy metals in polyolefins and comparison with results by TI-IDMS

2000

An inductively coupled plasma isotope dilution mass spectrometric (ICP-IDMS) method was developed as a suitable method - with respect to its sensitivity, precision, accuracy, and time-consumption - for the analysis of toxic heavy metal traces (Pb, Cd, Cr, and Hg) in polyolefins. Results for Pb, Cd, and Cr were compared with those obtained by thermal ionization isotope dilution mass spectrometry (TI-IDMS), which was used as a reference method. Because of its high first ionization potential and its high volatility mercury could not be determined by TI-IDMS. A multi-element spike solution, containing isotopically enriched 206Pb, 116Cd, 53Cr, and 201Hg, was used for the isotope dilution step. D…

Sensitive determination of methylenedioxylated amphetamines by liquid chromatography.

2001

Different strategies for the liquid chromatographic determination of methylenedioxylated amphetamines were evaluated: separation and detection of underivatized analytes by (i) UV or (ii) fluorescence, (iii) derivatization with 3,5-dinitrobenzoyl chloride followed by separation and UV detection of the derivatives formed and (iv) derivatization with 9-fluorenylmethyl chloroformate (FMOC) and subsequent separation and fluorimetric detection of the derivatives. The compounds tested were 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA) and 3,4-methylenedioxyethylamphetamine (MDE). On the basis of these studies, a new procedure for the chromatographic determination of…

Flow-injection spectrophotometric determination of arylamines and sulphonamides by diazotization and coupling in a micellar medium

1991

Abstract In a sodium dodecyl sulphate (SDS) micellar solution, the rate of coupling of a diazonium ion with N-(1- naphthyl)ethylenediamine (NED) increases greatly, the protonation of the resulting azo dyes takes place at higher pH values and the dyes are more soluble. These favourable features were applied to the development of a simple flow-injection spectrophotometric procedure for the determination of diazotizable substances of pharmaceutical interest. Limits of detection in the range 0.2–0.5 μg ml−1 (signal-to-noise ratio=3), with relative standard deviation of 0.7–3% (n=3) for 5 μg ml−1 standards, were obtained.

Hyaluronic acid and its derivatives in drug delivery and imaging: Recent advances and challenges.

2015

Hyaluronic acid (HA) is a biodegradable, biocompatible, nontoxic, and non-immunogenic glycosaminoglycan used for various biomedical applications. The interaction of HA with the CD44 receptor, whose expression is elevated on the surface of many types of tumor cells, makes this polymer a promising candidate for intracellular delivery of imaging and anticancer agents exploiting a receptor-mediated active targeting strategy. Therefore, HA and its derivatives have been most investigated for the development of several carrier systems intended for cancer diagnosis and therapy. Nonetheless, different and important delivery applications of the polysaccharide have also been described, including gene …

POLYASPARTAMIDE-POLYLACTIDE GRAFT COPOLYMERS WITH TUNABLE PROPERTIES FOR THE REALIZATION OF FLUORESCENT NANOPARTICLES FOR IMAGING

2015

Here, the synthesis and the characterization of novel amphiphilic graft copolymers with tunable properties, useful in obtaining polymeric fluorescent nanoparticles for application in imaging, are described. These copolymers are obtained by chemical conjugation of rhodamine B (RhB) moieties, polylactic acid (PLA), and O-(2-aminoethyl)-O'-methyl poly(ethylene glycol) (PEG) on α,β-poly(N-2-hydroxyethyl)-D,L-aspartamide (PHEA). In particular, PHEA is first functionalized with RhB to obtain PHEA-RhB with a derivatization degree in RhB (DDRhB ) equal to 0.55 mol%. By varying the reaction conditions, different amounts of PLA are grafted on PHEA-RhB to obtain PHEA-RhB-PLA with DDPLA equal to 1.9, 4…

Organochlorinated pesticides in sediments from the Lake Albufera of Valencia (Spain).

2005

Bottom sediment samples from 121 sites of the Lake Albufera of Valencia were analyzed. Dieldrin, endrin, heptachlor and op'-DDT were not detected (0.01 ng g(-1)) in 88-93% of the sites. Aldrin and HCB concentration ranges were between0.01 and 0.1 ng g(-1) in 86% and 94% of the sites, respectively. Heptachlor-epoxide and lindane 95% confidence intervals were 0.2-0.5 and 0.06-0.12, respectively. The greatest average concentration corresponds to pp'-DDE, pp'-DDD and pp'-DDT. The sum of six isomers and derivatives of the DDT average concentration reaches 2.1 ng g(-1), as opposed to 2.7 ng g(-1) for the sum of 13 pesticides considered. In the site with a major contamination, 27.0 ng g(-1) of pp'…

Simultaneous clean up of fish fat containing low levels of residues and separation of PCB from chlorinated pesticides by thin-layer chromatography

1974

Propyl substituted 4-arylimino-1,2,3-trihydroacridylnickel complexes: Their synthesis, characterization and catalytic behavior toward ethylene

2015

Propyl substituted 4-arylimino-1,2,3-trihydroacridylnickel dihalide complexes were designed and prepared by metal-induced template reaction with NiCl2 center dot 6H(2)O or (DME)NiBr2. They were characterized by infrared spectroscopy and elemental analysis. Single crystal X-ray crystallography of representative complex Ni3 revealed a distorted trigonal bipyramidal geometry around nickel. The catalytic activities of the title nickel complexes were negatively affected by propyl substituent on their backbone when comparing with the results by unsubstituted ones. With the activation of diethylaluminium chloride, all nickel complexes exhibited moderate activity (up to 5.10 x 10(5) g mol(-1)(Ni) h…