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  • 1
    Electronic Resource
    Electronic Resource
    MODIFICATION OF BUTTER OIL: EFFECTS OF SUPERCRITICAL CARBON DIOXIDE EXTRACTION AND INTERESETERIFICATION (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food lipids 1 (1994), S. 0 
    Details
    ISSN: 1745-4522
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Physical properties of lipid fractions isolated from anhydrous butter oil under various experimental conditions using supercritical carbon dioxide (SC-CO2) extraction, intereseterification or their combination, together with thermal modification were assayed in terms of triacylglycerol and fatty acid profiles. SC-CO2 process, at 35C and 2000 psi, preferentially extracted the low-molecular-weight triacylglycerols, did not result in any separation of cholesterol and extracted an approximately constant fraction (7%) of the material in each 2h interval. Combination of SC-CO2 extraction with thermal fractionation yielded a butter oil fraction with improved spreadability at refrigerator temperatures. At higher pressure and longer extraction time SC-CO2 resulted in decreased solvent selectivity without increased extraction yield. The triacylglycerol and fatty acid profiles of high pressure 6000 psi extracts were remarkably similar to those of the butter itself. Chemical interesterification of butter oil randomized the constituent fatty acids, giving products which contained higher proportions of the middle-range constituents. Thermal fractionation of interesterified butter yielded products only slightly enriched in higher molecular weight triacylglycerols, but interesterification of a solid obtained from thermal fractionation of butter gave a product greatly enriched in these compounds. Thus, modified lipid samples with distinct triacylglycerol and fatty acid compositions were prepared which may be used in different industrial applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-4522.1994.tb00247.x
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  • 2
    Electronic Resource
    Electronic Resource
    FURTHER DEVELOPMENT IN THERMAL MODIFICATION OF BUTTER OIL (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food lipids 1 (1993), S. 0 
    Details
    ISSN: 1745-4522
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Anhydrous butter oil was modified by acetone or n-hexane crystallization (10–20% w/w) over a temperature range of 29–17C without agitation, producing solid fractions with higher proportions of C44–C54 triacylglycerols vis-a-vis fractions obtained by classical thermal modification of butter oil. Similarly, recrystal-lization of a mixture of thermally isolated butter oil solids (S.25–S. 17C) in organic solvents at various temperatures yielded butter lipid fractions with significantly distinct chemical and physical properties. These lipid fractions showed to contain higher and lower proportions of C44–C54 and C26–C36 triacylglycerol respectively vis-a-vis solid fractions isolated via thermal modification of butter oil in organic solvents as the starting material(S.25–S. 17C) contained more of the former and less of the latter triacylglycerols than butter oil.Extraction of low molecular weight lipidsfrom solid fractions obtained by classic thermal modification of butter oil using acetone left a white powderous lipid which produced one sharp melting peak (53 C) in its DSC thermogram. The acetone treated fraction was enriched in C44–C52 triacylglycerols with a 2 to 6-fold reduction in C4–C10 fatty acids content.Recrystallization of a mixture of solid butter fractions isolated according to classical procedures at 29–21 C, over a temperature range of 35–21 C, yielded discrete fractions with profound differences in fatty acid and triacylglycerol profiles having very distinct physical properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-4522.1993.tb00240.x
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  • 3
    Electronic Resource
    Electronic Resource
    Persistence and degradation of PP993 pyrethroid, fonofos, and chlorpyrifos in a Quebec cornfield's soil (1989)
    Springer
    Bulletin of environmental contamination and toxicology 42 (1989), S. 172-176 
    Details
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01699396
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  • 4
    Electronic Resource
    Electronic Resource
    Determination of the s-methyl isomer in technical grade fenitrothion by gas chromatography and high speed liquid chromatography (1975)
    Springer
    Bulletin of environmental contamination and toxicology 13 (1975), S. 291-296 
    Details
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01685338
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  • 5
    Electronic Resource
    Electronic Resource
    Chromatographic optimization for the determination of traces of selenonium and arsonium cations by HPLC with on-line detection by AAS (1991)
    Springer
    Chromatographia 31 (1991), S. 481-488 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Selenonium and arsonium cations ; AAS detection ; Chromatographic optimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Optimal mobile phase compositions were determined for the separation of selenonium ions [trimethylselenonium, (2-hydroxyethyl)dimethylselenonium and (2-acetoxyethyl)dimethylselenonium] and, separately, for arsonium ions (tetramethylarsonium, arsenobetaine, and arsenocholine) by HPLC with detection by atomic absorption spectrometry (AAS). Surface response methodologies were used to predict the variations in detector response (peak area), capacity factors, and selectivities as a function of the mobile phase composition. For selenonium analytes, a mixture of triethylammonium and trimethylsulfonium ions in the methanol-1% acetic acid mobile phase provided a compromise between resolving power and chromatographic efficiency. By contrast, optimum chromatography of the arsonium analytes was obtained by replacing onium additives in the mobile phase by picrylsulfonic acid. For both selenonium and arsonium analytes, the dominant interaction with the stationary phase was with residual silanols and improvements to the chromatographic performance of these analytes resulted in appreciable decreases in their limits of detection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02262393
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis of 14C-radiolabelled trimethyllead chloride (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 1 (1987), S. 251-260 
    Details
    ISSN: 0268-2605
    Keywords: 14C labelling ; Trimethyllead ; Organic lead ; Grignard synthesis ; Electrochemical synthesis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two synthetic routes to 14C-labelled trimethyllead chloride ((CH3)3PbCl) from 14C-methyl iodide (CH3I) were investigated. Alkylation of (CH3)3PbCl with labelled methylmagnesium halide, on a microscale, was less efficient for the synthesis of tetramethyllead ((CH3)4Pb) than was an electrochemical reduction of labelled CH3I at a sacrificial lead cathode. In the Grignard approach, unlabelled decyl bromide served as an initiator for the reaction of 14C-CH3l with excess Mg and as a carrier during the subsequent alkylation of (CH3)3PbCl. In the electrochemical approach a two-compartment cell, using dimethylformamide as solvent and sodium perchlorate as supporting electrolyte, offered several advantages over a single compartment reactor. The labelled (CH3)4Pb from both reactions was isolated by extraction, converted to (CH3)3PbCl by controlled oxidation with HCl and purified by thin layer chromatography.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aoc.590010307
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  • 7
    Electronic Resource
    Electronic Resource
    Synthesis, storage, and transfer of [210Pb]-(CH3)3PbCl across tomato fruit cuticle (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 3 (1989), S. 89-98 
    Details
    ISSN: 0268-2605
    Keywords: Lead-210 ; organolead ; synthesis ; migration ; plant tissue ; analysis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An improved synthetic route to [210Pb]-(CH3)3PbCl is described in which chelated 210Pb2+ is methylated to [210Pb]-(CH3)4Pb with methylmagnesium bromide (CH3MgBr) in the presence of methyl iodide. Controlled oxidation of the product with anhydrous hydrochloric acid and purification of the crude product by reversed-phase high-pressure liquid chromotography (HPLC) resulted in [210Pb]-(CH3)3PbCl in 71% radiochemical yield. Whereas storage of the purified product at -10 °C resulted in complete conversion to Pb2+ during one year, storage in 20% acetic acid at 4 °C resulted in less than 15% decomposition during six months. Periodic complexometric extractions to remove 210Pb radioactive daughters (210Bi, 100% β, Emax = 1.16 MeV; 210Po, 100% α, E = 5.305 MeV) from the storage solution did not alter the rate of decomposition. The rate of translocation of [210Pb]-(CH3)3Pb+ across an isolated tomato cuticle was approximately twice the rate of transfer of inorganic lead(II) and was not influenced by the presence of increasing amounts of disodium ethylenediamine-tetra-acetate.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aoc.590030109
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  • 8
    Electronic Resource
    Electronic Resource
    Ionic alkylleads in avian tissues from aquatic and terrestrial environments (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 2 (1988), S. 233-238 
    Details
    ISSN: 0268-2605
    Keywords: Alkylleads ; determination ; avian tissues ; methylation ; residues ; pigeons ; ducks ; speciation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ionic alkyllead concentrations in soft tissues of pigeons from urban Montreal and environs were appreciably different from the variety and concentrations of alkyllead analytes which characterized mallard ducks culled from a sanctuary in eastern Ontario. The major toxicant in pigeons, triethyllead (Et3Pb+) reflected the exclusive use of tetraethyllead as a gasoline additive in both regions. Urban colonies of pigeons were characterized by significantly greater concentrations of Et3Pb+ than were specimens from a suburban/rural colony. In contrast, the major toxicant in ducks was trimethyllead although six other alkyllead analytes were also observed. An environmentally mediated methylation of Pb2+ which is more active in (but not restricted to) aquatic environments is postulated to account for the ubiquity of trimethyllead in ducks.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aoc.590020305
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  • 9
    Electronic Resource
    Electronic Resource
    Selenium speciation by high-performance liquid chromatography with on-line detection by atomic absorption spectrometry (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 9 (1995), S. 149-158 
    Details
    ISSN: 0268-2605
    Keywords: selenium speciation ; high-performance liquid chromatography-atomic absorption spectrometry ; seleno oxyanions ; selenoamino acids ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several approaches to the determination of selenomethionine, selenocystine, selenite and selenate by high-performance liquid chromatography with online detection by atomic absorption spectrometry are described. The N-2,4-dinitrophenyl derivatives of selenomethionine, selenoethionine, selenocystine and phenylmercury(II) cystineselenoate were recovered from aqueous solution, separated on a Nucleosil 5-NO2 reversed-phase HPLC column with a methanolic mobile phase containing acetic acid and triethylamine, and detected with a quartz thermochemical hydride-generating interface-atomic absorption spectrometry (AA) system. The restriction of having to perform chromatography with an organic mobile phase (to support the combusion process) was overcome with a new interface design capable of operation with either organic or aqueous HPLC mobile phases. Using aqueous acetic acid (0.015% v/v) containing 0.1% (w/v) ammonium acetate delivered at 0.5cm3 min-1, selenate, selenite, selenomethionine, selenocystine and selenoethionine were separated virtually to baseline on a cyanopropyl-bonded phase HPLC column. Other selenium compounds which were investigated included methane seleninic and methane selenonic acids as well as the crude oxidation product mixtures resulting from the treatment of selenomethionine and selenocystine with hydrogen peroxide. A procedure for extracting selenate, selenite, selenomethionine, selenocystine and selenoethionine from spiked water or ground feed supplement into liquefied phenol resulted in acceptable recoveries for the latter four analytes but was unacceptably low for selenate.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aoc.590090209
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