Search results for "ethers"

Enantiomeric separation of chiral phenoxy acid herbicides by electrokinetic chromatography. Application to the determination of analyte-selector appa…

2001

The enantiomeric resolution of chiral phenoxy acid herbicides was performed by electrokinetic chromatography using a cyclodextrin as chiral pseudophase (CD-EKC). A systematic evaluation of several neutral and charged cyclodextrins was made. Among the cyclodextrins tested, (2-hydroxy)propyl beta-cyclodextrin (HP-beta-CD) was found to be the most appropriate for the enantioseparation of phenoxy acids. The influence of some experimental conditions, such as nature and pH of the background electrolyte, chiral selector concentration, and temperature, on the enantiomeric separation of phenoxy acids was also studied. The use of a 50 mM electrolyte solution in ammonium formate at pH 5 and a temperat…

Ab initio study of halogenated diphenyl ethers. NMR chemical shift prediction

2000

Analyses of known and new types of polyhalogenated aromatic substances in oven ash from recycled aluminium production

2003

Abstract Persistent aromatic bromine, chlorine and mixed chlorine-bromine compounds were analysed from recycled aluminium smelter (ALS) ashes to explore the impact of brominated flame retardants (BFR) on their formation. Polybrominated diphenyl ethers (PBDE) were the most abundant original BFRs found. Induction furnace ash contained tetra- to octa-BDEs about 2000 ng g −1 in similar congener ratios as the original scrap, but contents of nona- and deca-BDEs were only 25 and 5 ng g −1 indicating their significant degradation in ALS process. In the most non-polar fraction, PCB levels and profiles were similar as earlier ALS ash samples in 1990s. The highest PCB level measured was that of deca-C…

Structural effects of macrocyclic compounds and their partition in sodium dodecylsulphate aqueous solutions

2003

The partition of 1,4,7,10,13,16-esaoxacyclooctadecane (18C6), 4,7,13,16-tetraoxa-1,10-diazacyclooctadecane (2.2), 2,5,8,11,14,17-esaoxabicyclo[16.4.0]dicosane (B18C6) and 2,5,8,15,18,21-esoxatricyclo[20.4.0.09.14]esacosane (Cy218C6) in sodium dodecyl sulfate (SDS) aqueous solutions and their effect on the structure of surfactant aggregates has been investigated by small-angle neutron scattering. Results from data analysis have shown that by increasing macrocycle concentration the SDS micelles dimensions reduce for all systems investigated. At the same time information on macrocycles partition between the micellar and the continuous phase have been obtained. It was found that an appreciable …

Complexation behaviour of hexadentate ligands possessing N2O4and N2O2S2cores: differential reactivity towards Co(ii), Ni(ii) and Zn(ii) salts and str…

2004

Reactions of divalent metal salts of Co, Ni and Zn with 1,2-di(salicylaldimino-o-phenylthio) ethane (H2L1) and 1,2-di(naphthaldimino-o-phenylthio) ethane (H2L2), having N2O2S2 cores, and 1,2-di(O-salicylaldimino-o-hydroxyphenyl) ethane (H2L3), having a N2O4 core, have been explored. Out of the three ligands and the nine products obtained from the corresponding reactions, two ligands and seven products were crystallographically characterized. However, all the ligands and the products were characterized by analytical and spectral methods. Reaction of H2L1 and H2L2 with Co(II) salts results in oxidative cleavage of the C-S bond to produce a Co(III) product bound to two dissimilar tridentate li…

The synthesis of fluorinated heteroaromatic compounds. Part 2. Five-membered rings with two heteroatoms. A review

2007

Optimization of a microwave-assisted extraction large-volume injection and gas chromatography–ion trap mass spectrometry procedure for the determinat…

2006

Abstract A sensitive and rapid method for the determination of polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs) and polychlorinated naphthalenes (PCNs) in sediment samples is proposed. The method involving microwave-assisted extraction (MAE) and large-volume injection (LVI) gas chromatography (GC)–ion trap mass spectrometry (ITMS), and the experimental conditions were optimized using the statistical design of experiments (DOE). A Plackett–Burman (P–B) design was chosen to estimate the influence of five factors, such as resonance excitation voltage (EV), isolation time (IT), excitation time (ET), ion source temperature (IST) and electron energy (EE) on the analytical r…

Miniaturized matrix solid phase dispersion procedure and solid phase microextraction for the analysis of organochlorinated pesticides and polybromina…

2009

Abstract This work has developed a miniaturized method based on matrix solid phase dispersion (MSPD) using C18 as dispersant and acetonitrile–water as eluting solvent for the analysis of legislated organochlorinated pesticides (OCPs) and polybrominated diphenylethers (PBDEs) in biota samples by GC with electron capture (GC-ECD). The method has compared Florisil®-acidic Silica and C18 as dispersant for samples as well as different solvents. Recovery studies showed that the combination of C18–Florisil® was better when using low amount of samples (0.1 g) and with low volumes of acetonitrile–water (2.6 mL). The use of SPME for extracting the analytes from the solvent mixture before the injectio…

The occurrence of Dechlorane Plus and related norbornene-based flame retardants in Baltic wild salmon (Salmo salar)

2015

Twenty five Baltic wild salmon (Salmo salar) specimens were analysed for the content of Dechlorane-related compounds (DRCs). Out of the ten analysed DRCs, seven compounds were detected in the muscle tissues of salmon, including Dechlorane (Dec) 602, Dec 603, syn- and anti-stereoisomers of Dechlorane Plus (DP), Dechlorane Plus monoadduct (1,3-DPMA), hexachlorocyclopentadienyl-dibromocyclooctane (DBHCTD), and Mirex. The concentrations of Dec 604 and two DP dechlorinated compounds - decachloropentacyclooctadecadiene (Cl10DP) and undecachloropentacyclooctadecadiene (Cl11DP) - were below the limit of detection in all samples. The aggregated concentrations of DRCs (ΣDRC) were in the range of 551-…

Occurrence of polybrominated diphenyl ethers, perfluorinated compounds, and nonsteroidal anti-inflammatory drugs in freshwater mussels from Latvia.

2018

Abstract The occurrence of polybrominated diphenyl ethers (PBDE), perfluorinated compounds (PFC), and nonsteroidal anti-inflammatory drugs (NSAID) in Latvian freshwater ecosystems was evaluated by using filter-feeding mussels as bioindicators. Twenty four samples of mussels were collected from freshwater bodies throughout the territory of Latvia during the summer of 2017. PBDE contamination was ubiquitous, reaching the highest total concentration of 193.2 pg g−1 w.w. BDE-209 was the most abundant compound, followed by penta-BDE components BDE-49, -100, −99, −153, −154, and −47 in decreasing order. The levels of PFCs in Latvian mussels were generally lower than those reported from other regi…