Baseline isotopic data of polyhalogenated compounds

The δ²H- and δ¹³C-values of polyhalogenated compounds were determined by EA-IRMS. Most of the compounds were related to the chloropesticides DDT and its metabolites, hexachlorocyclohexanes, and toxaphene, as well as several polybrominated compounds such as bromophenols and -anisoles. δ²H-values ranged between −235‰ and +75‰ whereas δ¹³C-values were found in the range −22‰ to −38‰. No correlation between δ²H- and δ¹³C-values could be identified. Comparative analysis clarified that bromophenols and the corresponding bromoanisoles may vary in their isotopic distribution. ²H NMR was used to quantify abundances of ²H isotopomers. Quantification of isotopomers of 2,4-dibromophenol and 2,4-dibromoanisole proved that both compounds from different suppliers do not originate from the same source. Differences in the δ²H-values of two toxaphene products were further investigated by the synthesis of products of different degree of chlorination from camphene. It was shown that the δ¹³C-values remained mostly unaltered as was expected since no carbon is lost in this procedure. However, the reaction products became enriched in ²H with increasing degree of chlorination. Different δ²H-values of the starting material will also impact the δ²H-values of the chlorination products.     

Photodegradation of polystyrene sensitised by polyhalogenated compounds

The photosensitised degradation of polystyrene by polyhalogenated compounds has been studied. During the sensitised photo-oxidative degradation in film and in benzene and methylene chloride solutions, there is a rapid decrease of molecular weight observed by viscosity and GPC measurements. A remarkable after-effect, with a decrease in polymer molecular weight, was also detected. The reaction rates and quantum yields for main-chain scissions are greatly increased by dibromotetrachloroethane, tetrabromophenylpropane, tetrabromononane and carbon tetrabromide.The most probable mechanism of photosensitised degradation involves initial formation of bromine atoms which preferentially attack the polymer by hydrogen atom abstraction and bromination. The effect of oxygen on the degradation is also discussed.     

Selective additions of polyhalogenated compounds to chloro substituted ethenes catalyzed by a copper complex

The Cu complex Cu(L)_nCl (L=2-propylamine) has been found to be an advantageous catalyst for the addition of polyhalogenated compounds to chloro substituted ethenes; the 11 adducts were formed almost exclusively in up to 71% yield.

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, , Cu(L)_nCl (L=2-), ; 71% 11.

     

Photoreduction of polyhalogenated anthraquinones by direct electron transfer from alcohol

Polyhalogenated anthraquinones such as perfluoroanthraquinone, 1,2,3,4-tetrafluoroanthraquinone, and 1,2,3,4-tetrachloroanthraquinone are photoreduced in ethanol via direct electron transfer from ethanol. A dramatic switch-over from hydrogen-atom abstraction to electron transfer is induced by mixing ofππ with nπ^* states in their T₁ state and the enhanced electron-accepting character of polyhalogenated anthraquinones.     

Evaluation of the use of liquid dishwashing compounds to control bacteria in kitchen sponges

A test procedure for evaluating the effect of adding commercial liquid hand dishwashing detergents to kitchen sponges to control microbial growth is described. Claims for this type of application are being made on dishwashing detergents throughout the world. In this evaluation, commercially available kitchen sponges were stripped of antimicrobial compounds. Sponges were then inoculated with a pool of 7 microorganisms which consisted of gram positives, gram negatives, and yeast. Inoculated sponges were treated with the detergent as recommended by the manufacturer and allowed to incubate for 16 h at ambient temperature. Surviving microorganisms were then quantitated using either the spiral or pour plate method. Tests were run using both clean sponges and sponges soiled with 0.5% nonfat dry milk (NFDM). Untreated sponges showed stasis or slightly increased bacterial populations after the incubation period in the absence of NFDM. Significant increases of up to 3 log cfu/mL were observed for untreated sponges when soiled with NFDM. Statistically significant reductions were observed for clean sponges (99.8-99.9998%) and sponges soiled with NFDM (87.6-99.9%) when detergents making "antibacterial sponge" claims were added to the inoculated sponges. Statistically significant differences between detergents making "antibacterial sponge" claims were also observed.     

Pyranosylmagellanicus a novel structural class of polyhalogenated acetogenins from Ptilonia magellanica

Three naturally occurring pyranosyl-like polyhalogenated metabolites 1-3 as well as their likely biogenetic precursor, the linear compound 4, have been isolated from the red alga Ptilonia magellanica. They are the first compounds within the genus that incorporate chlorine in their network. Compound 3 have structural features reminiscent of the universal chemical signal AI-2 (autoinducer-2) for bacterial communication.     

Ion mobility spectrometry of volatile compounds from Iberian pig fat for fast feeding regime authentication

Characteristic ion mobility spectra for volatile compounds present in fat were used to authenticate the feeding regime of Iberian pigs. Volatile compounds were obtained by heating the solid samples at 150 degrees C for 40 min. This produced a headspace that was introduced in the spectrometer ionization chamber by means of a highly purified nitrogen stream. The spectra thus, obtained for the fat samples were processed chemometrically in order to assess their usefulness for discriminating meat from free-range pigs fed on pasture and acorns and confined pigs fed with commercial feed including high-oleic acid products. Principal component analysis was used as both an exploratory tool and a variable reduction method, and linear discriminant analysis was employed to classify 65 subcutaneous fat samples according to pig feeding regime. Only 2.3% of the samples from pigs reared in confinement were misclassified. 95.5% of the free-range samples were correctly predicted.     

Total synthesis of 8-desoxy-isocaespitol,A new polyhalogenated sesquiterpene from Laurencia caespitosa

The structure of a new polyhalogenated bisabolene-type sesquiterpene, $\text{2}$, isolated from $\text{Laurencia caespitosa}$ has been elucidated by chemical and spectral means and confirmed by a three-step synthesis starting from commercial farnesol.     

Authentication of fattening diet of Iberian pigs according to their volatile compounds profile from raw subcutaneous fat

The composition of volatile components of subcutaneous fat from Iberian pig has been studied. Purge and trap gas chromatography−mass spectrometry has been used. The composition of the volatile fraction of subcutaneous fat has been used for authentication purposes of different types of Iberian pig fat. Three types of this product have been considered, montanera, extensive cebo and intensive cebo. With classification purposes, several pattern recognition techniques have been applied. In order to find out possible tendencies in the sample distribution as well as the discriminant power of the variables, principal component analysis was applied as visualisation technique. Linear discriminant analysis (LDA) and soft independent modelling by class analogy (SIMCA) were used to obtain suitable classification models. LDA and SIMCA allowed the differentiation of three fattening diets by using the contents in 2,2,4,6,6-pentamethyl-heptane, m-xylene, 2,4-dimethyl-heptane, 6-methyl-tridecane, 1-methoxy-2-propanol, isopropyl alcohol, o-xylene, 3-ethyl-2,2-dimethyl-oxirane, 2,6-dimethyl-undecane, 3-methyl-3-pentanol and limonene.     

Supercritical fluid extraction of polyhalogenated pollutants from aquaculture and marine environmental samples: a review

This article focuses on the state-of-the-art in sample preparation using supercritical fluid extraction (SFE), to monitor the content of polyhalogenated pollutants in aquaculture and marine environmental samples. Marine sediments and biological applications, including several types of samples matrices (fish, shellfish, seaweed and fish feed) and analyte groups (polychlorinated biphenyls (PCBs), polybrominated biphenyls (PBBs), polybrominated diphenylethers (PBDEs), polychlorinated dibenzo-p-dioxin (PCDD)/Fs and organochlorinated pesticide (OCPs)) are discussed with respect to SFE use and optimisation of conditions. We also discuss the great analytical potential of SFE, the integration of the extraction and clean-up steps for rapid sample processing justifying its use for routine work. The most recent SFE applications to the determination of these pollutants in marine environmental (biota and sediment) samples, published in the last 15 years, are reviewed.     

Volatile compounds in virgin olive oil: occurrence and their relationship with the quality

The stimulation of the human sensory receptors by volatile compounds present in virgin olive oils gives rise to the sensory attributes that describe its delicate and fragrant aroma. The composition of the volatile compounds and their biogenesis is briefly illustrated. Analytical methodologies for evaluating the volatile fraction and the sensory properties of virgin olive oils are elucidated. Compounds responsible for typical flavours are examined and the influence of the main factors on the composition of volatile compounds is discussed. The origin of off-flavours are also described and the consequent changes of volatile composition and of sensory characteristics are analysed. The relationships between volatile compounds and sensory attributes are discussed.     

Further understanding of fat biology: Lessons from a fat fly

Obesity is a leading risk factor for insulin resistance, hypertension, hyperlipidemia, and cardiovascular complications, collectively referred to as metabolic diseases. Given the prevalence of obesity and its associated medical problems, new strategies are required to prevent or treat obesity and obesity-related metabolic effects. Here we summarize contributors of obesity, and molecular mechanisms controlling adipogenesis from studies in mammalian systems. We also discuss the possibilities of using Drosophila as a genetic model system to advance our understanding of players in fat biology.     

Identification of volatile aroma compounds in processed cheese analogues based on different types of fat

The simple and rapid solid-phase micro-extraction method using gas chromatography was used for the identification and quantification of volatile aroma compounds in various types of processed cheese analogues produced from different types of fat (butter, butter oil, coconut oil, palm oil, and sunflower oil). In total, 31 organic compounds belonging to five chemical groups were identified, with the alcohols and fatty acids quantitatively predominant. The contents of the aroma compounds (the so-called aroma profiles) of the analogues and corresponding fats used as raw materials were compared. Significant differences (p < 0.05) were found between samples. The highest total content of aroma compounds was found in coconut oil analogue ((547.30 ± 9.82) mg kg^?1), the lowest in palm oil analogue ((372.01 ± 16.16) mg kg^?1). The concentrations of aroma compounds in fats were substantially lower (p < 0.05) than in analogues. Hence, the largest number of aroma analogues came from Edam cheese used for production as a protein source.     

Conditions for occurrence of long-chain oxidation reaction of organic compounds by persulfate in an aqueous medium

Using a kinetic model of the routes of unbranched radical-chain processes, an expression was found for the rate of the aqueous solution. The possible conditions for the occurrence of the process over a wide range of concentrations of persulfate and the organic compound were analyzed.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 26, No. 3, pp. 360–365, May–June, 1990.     

Mechanical and kinetic studies of the formation of polyhalogenated dibenzo-p-dioxins from hydroxylated polybrominated diphenyl ethers and chlorinated derivatives

Hydroxylated polybrominated diphenyl ethers (OH-PBDEs),which may be generated from PBDEs, are more toxic than their matrix and have been detected in organisms. In this article, we have focused on the gas phase formation of polyhalogenated dibenzo-p-dioxins from several OH-PBDEs and their chlorinated derivatives. All of the geometries and frequencies are calculated at the MPWB1K/6-31+G(d,p) level of theory. The single point energy is obtained at the MPWB1K/6-311+G(3df,2p) level. Rate constants of each step have been calculated over a wide range of 200-2000 K using the canonical variational transition state (CVT) theory with small curvature tunneling (SCT) contribution. The rate equations are shown through Arrhenius formulas. The presence of chlorine atoms increases the reaction barrier for the formation of major products.