Search results for "flame"

Enhancing extraction performance of organophosphorus flame retardants in water samples using titanium hierarchical porous silica materials as sorbent…

2021

Abstract A sorbent for the extraction of organophosphorus flame retardants has been proposed, based on UVM-7 (University of Valencia Materials) mesoporous silica doped with titanium. Designed cartridges have been applied to the extraction and preconcentration of flame retardants in water samples, followed by gas chromatography coupled to a mass spectrometry detector. Firstly, UVM-7 materials with different contents of titanium were synthesized and characterized by several techniques, thus confirming the proper mesoporous architecture. The potential of these materials was assessed in comparison with their morphological properties, resulting Ti50-UVM-7 the best solid phase. Several extraction…

New perspectives on diastereoselective determination of hexabromocyclododecane traces in fish by ultra high performance liquid chromatography-high re…

2014

a b s t r a c t A new analytical method is presented for diastereoisomer-specific identification and quantitation of hexabromocyclododecanes (HBCD) in fish samples. The method is based on extraction of the target analytes from samples with a mixture of organic solvents, with further three-stage clean-up includ- ing destructive removal of matrix components with sulphuric acid and acid-impregnated silica gel, and Florisil adsorption column chromatography. Ultra high performance liquid chromatography (UPLC) cou- pled with high resolution (HR) Orbitrap mass spectrometry featuring heated electrospray ionization (HESI-II) interface operated in negative ion mode was employed for the identification…

Contribution à l’étude de la fraction insaponifiable de trois huiles d’olive issues des variétés Guasto, Rougette et Blanquette plantés dans l’est al…

2010

The sterol profile of three Algerian virgin olive oils produced from Guasto, Blanquette and Rougette cultivar’s, varieties grown in the East of the country, was established by gas chromatography using a flame ionization detector and coupled to mass spectrometry. Four sterol compounds were identified and characterized in the three oils which are, sitosterol always predominant (43-66%), delta 5-avenasterol (8-13%), stigmasterol (≤ 1,5%) and campesterol (1-2%); one methyl sterol (4-methylsterol) : citrostadienol (4-7%) and two triterpenic alcohols : 24-methylene cycloartanol (10-33%) and cycloartenol (3-13%). These results vary according to campany and variety. Our study shows that most of the…

Bromēto liesmas slāpētāju noteikšana medību gaļas paraugos ar augstas izšķirtspējas masspektrometrijas metodēm

2017

Bromēto liesmas slāpētāju noteikšanas medību gaļas paraugos ar augstas izšķirtspējas masspektrometrijas metodēm. Bāliņš Rolands, zinātniskais vadītājs: Dr. ķīm., Dzintars Začs, konsultante: Ķīm. maģ., doktorante Jekaterina Rjabova. Maģistra darbs, 47 lappuses, 9 attēli, 21 tabula, 30 literatūras avoti, 2 pielikumi. Latviešu valodā. Maģistra darbā ir apkopota literatūra par analizētajiem savienojumiem, to pielietošanu, toksiskumu, izplatību dabā un to analīžu metodēm. Iegūtie rezultāti ir apkopoti tabulu un diagrammu veidā. Darbā tika veikta bromēto liesmas slāpētāju tetrabrom bisfenola A (TBBPA), heksabromciklododekāna (HBCDD) un polibromēto difenil ēteru (PBDEs) noteikšana medījumu gaļas p…

The Italian Method of la drammatica: its Legacy and Reception

2014

Radiation curing of diacrylate glycerolate of bisphenol-A in the presence of an organically modified montmorillonite for the production of flame-resi…

2006

Polymerization of an acrylate derivative of bisphenol-A by ionizing radiation in the presence of an organically modified montmorillonite was carried out in order to produce a flame-retardant composite. The measurement of the thermal effect during irradiation indicates that radiation curing of pure resin and resin-clay mixtures occurred in both cases. Moreover, differential scanning calorimetry and dynamic mechanical thermal analysis showed that a curing completion can be obtained by thermal curing after irradiation with a significant increase of the glass transition temperature. The morphology was investigated by X-ray diffraction and transmission electron microscopy. These have indicated t…

Thermal Stability and Flame Retardancy of Polypropylene Composites Containing Siloxane-Silsesquioxane Resins

2018

A novel group of silsesquioxane derivatives, which are siloxane-silsesquioxane resins (S4SQ), was for the first time examined as possible flame retardants in polypropylene (PP) materials. Thermal stability of the PP/S4SQ composites compared to the S4SQ resins and neat PP was estimated using thermogravimetric (TG) analysis under nitrogen and in air atmosphere. The effects of the non-functionalized and n-alkyl-functionalized siloxane-silsesquioxane resins on thermostability and flame retardancy of PP materials were also evaluated by thermogravimetry-Fourier transform infrared spectrometry (TG-FTIR) and by cone calorimeter tests. The results revealed that the functionalized S4SQ resins may for…

Molecular orbital studies on brominated diphenyl ethers. Part II—reactivity and quantitative structure–activity (property) relationships

2005

Polybrominated diphenyl ethers (PBDEs) are widely used as flame retardants and are increasingly turning up in the environment. Their structural similarities to polychlorinated biphenyls and thyroid hormones suggest they may be a risk to human health. The present study examines the reactivity of brominated diphenyl ethers (BDEs) on the basis of the electronic structures as calculated by semiempirical AM1 self-consistent field molecular orbital (SCF-MO) method. Frontier orbital energies were used to elucidate the reactivity of BDEs in electrophilic, nucleophilic and photolytic reactions. From an examination of the frontier electron densities, the regioselectivity, or orientation, of metabolic…

Copper, iron, and zinc contents in human milk during the first three months of lactation: A longitudinal study

2000

The aim of the study has been to analyze the evolution of copper, iron, and zinc contents in human milk, from colostrum to the third postpartum month, following a longitudinal design, under specific conditions of sample collection and to apply an analytical procedure previously optimized to reduce any variation outside physiological lactation. The copper, iron, and zinc concentrations in 144 milk samples from 39 healthy puerpera women, were analyzed in five stages by flame atomic absorption spectrometry, following a standardized protocol. Copper presented a gradual decrease from 0.38 mg/L to 0.19 mg/L by the 90th day; the particular analysis from colostrum to transitional milk manifested th…

Chromatography with dense gases

1992

A capillary restrictor for supercritical fluid chromatography (SFC) with CO2 was made by using a micro torch and fine emery cloths or grinding blocks. This restrictor could be drawn out either directly from the end of the analytical capillary column, or from a short piece of any capillary, which was then connected to the analytical column by standard techniques. It was found that the base current of a flame ionisation detector (FID) depends strongly on the position of the capillary end with respect to the FID flame tip and on the CO2 grade, of course. Best results have been achieved at around 5 to 7 mm distance between the restrictor and the flame tip ends, and using SFC grade CO2.