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Gas Chromatography (gas + chromatography)
Kinds of Gas Chromatography Terms modified by Gas Chromatography Selected AbstractsSPME/GC/MS and sensory flavour profile analysis for estimation of authenticity of thyme honeyINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 2 2007Demet Manna Summary Volatiles of six commercially obtained thyme honey samples and a pure thyme honey sample were extracted and analysed by Solid phase micro extraction (SPME)/Gas chromatography (GC)/Mass spectrometry (MS) procedure. Excess amount of volatiles such as thymol (trace) and carvacrole (0.66%) that originate from thyme plants indicated adulteration by thyme essential oil in one of the commercial samples. Sensory flavour profile analysis showed that the flavour of pure thyme honey sample consisted of: sweet, honey, lilac, bitter almond, thyme, violet, waxy, sour, ginger, caramel and rose characters. Adulterated honey was detected to be the sweetest sample involving intense thyme flavour without honey character. 3,4,5-Trimethoxybenzaldehyde which is a volatile not found in other unifloral honeys, seems to be a possible marker, but further studies with certified thyme honey samples are necessary in order to confirm the utility of this compound in estimation of authenticity. [source] THE STUDY OF NABATAEAN ORGANIC RESIDUES FROM MADÂ'IN SÂLIH, ANCIENT HEGRA, BY GAS CHROMATOGRAPHY , MASS SPECTROMETRY,ARCHAEOMETRY, Issue 4 2009C. MATHE Four Nabataean samples collected in some of the monumental tombs of Madâ'in Sâlih, ancient Hegra, in Saudi Arabia, have been studied by gas chromatography coupled with mass spectrometry. These samples are textile fragments that are either covered with a black layer or bound together with some black amorphous substance. Fatty acids and triterpenoic compounds were detected. Eight triterpenic compounds were identified: ursa-9(11),12-dien-3-ol, ursa-9(11),12-dien-3-one, olean-9(11),12-dien-3,-ol, ,-amyrone, ,-amyrin, ,-amyrone, ,-amyrin and lupeol. The resinous chemical composition and these pentacyclic alcohols, in considerable proportion, indicate a resin of the Burseraceae family, possibly of the genus Canarium. [source] Analysis of Volatile Compounds in Beef Fat by Dynamic-Headspace Solid-Phase Microextraction Combined with Gas Chromatography,Mass SpectrometryJOURNAL OF FOOD SCIENCE, Issue 5 2008A. Watanabe ABSTRACT:, A solid-phase microextraction (SPME) technique has been applied to the determination of the volatile compounds, including diterpenoids and lactones, in cooked beef fat. The ability of static-headspace SPME to extract lactones was disappointing, regardless of the type of SPME fiber or the temperature used. Dynamic-headspace SPME extraction with 50-/30-,m divinylbenzene-Carboxen on a polydimethylsiloxane fiber at 100 °C, by contrast, enabled the analysis of volatiles, including delta-lactones, gamma-lactones, and diterpenoids, with 50-/30-,m divinylbenzene-Carboxen on a polydimethylsiloxane fiber at 100 °C. Fifty-three compounds were identified from only 0.20 g of rendered beef fat, and 76% of these showed reliable peak size repeatability: the coefficient of variation was less than 10% on the total ion chromatograms obtained from gas chromatography,mass spectrometry (GC,MS) analysis. Some lactones showed higher CV values (>10%), but single-ion mode GC,MS analysis reduced them to 10% or less. In a study of beef samples available to the Japanese market, our analytical procedure revealed significantly higher levels of 1-hexanol, octadecane, ethyl tetradecanoate, gamma-nonalactone, but lower levels of delta-decalactone, delta-dodecalactone, and neophytadiene, in Japanese Black cattle than in beef imported from Australia. [source] Age Determination of Ballpoint Pen Ink by Thermal Desorption and Gas Chromatography,Mass Spectrometry,JOURNAL OF FORENSIC SCIENCES, Issue 4 2008Jürgen H. Bügler Ph.D. Abstract:, Two main approaches can be used for determining the age of an ink: indirect dating and direct dating. Indirect dating is based on the chemical analysis of an ink followed by comparison with known samples in a reference collection. The collection should contain information about the inks including the market introduction dates. This approach may allow for an anachronism to be detected. The second concept is based on measuring ink components that change with age. The analysis of solvents in ballpoint inks may be a useful parameter for determining the age of ink on paper. In a previous study, the authors demonstrated that thermal desorption of ink directly from paper, followed by chemical analysis using gas chromatography,mass spectrometry (GC,MS), is a promising procedure for characterizing ink-binder resins and solvents. Preliminary tests showed that monitoring the evaporation of ink solvent from ink on paper is not a suitable method for ink dating. Thermal analysis of ink on paper in two steps revealed that fresh ink releases a relative amount of solvent at a certain low temperature in a defined period of time, which decreases as the ink ages. As a consequence, this relative amount of solvent released at a certain low temperature, and its decrease with time, can be used to estimate ink age. This age-dependent parameter was studied in 85 different inks ranging in age from 1 week to 1.5 years. It was found that some inks showed a significant decrease of this parameter up to an age of several months, and that the aging process can be monitored within this period. For other inks, however, the age-dependent parameter decreases relatively fast, e.g., within a few days, to a constant level, which can be too fast for casework. Based on these results, a general procedure for assessing the age of ballpoint pen inks on paper was developed. [source] Blood Cyanide Determination in Two Cases of Fatal Intoxication: Comparison Between Headspace Gas Chromatography and a Spectrophotometric Method*JOURNAL OF FORENSIC SCIENCES, Issue 6 2007Veniero Gambaro M.Sc. Abstract:, Blood samples of two cases were analyzed preliminarily by a classical spectrophotometric method (VIS) and by an automated headspace gas chromatographic method with nitrogen-phosphorus detector (HS-GC/NPD). In the former, hydrogen cyanide (HCN) was quantitatively determined by measuring the absorbance of chromophores forming as a result of interaction with chloramine T. In the automated HS-GC/NPD method, blood was placed in a headspace vial, internal standard (acetonitrile) and acetic acid were then added. This resulted in cyanide being liberated as HCN. The spectrophotometric (VIS) and HS-GC/NPD methods were validated on postmortem blood samples fortified with potassium cyanide in the ranges 0.5,10 and 0.05,5 ,g/mL, respectively. Detection limits were 0.2 ,g/mL for VIS and 0.05 ,g/mL for HS-GC/NPD. This work shows that results obtained by means of the two procedures were insignificantly different and that they compared favorably. They are suitable for rapid diagnosis of cyanide in postmortem cases. [source] The application of carbon isotope ratio mass spectrometry to doping controlJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 7 2008Adam T. Cawley Abstract The administration of synthetic steroid copies is one of the most important issues facing sports. Doping control laboratories accredited by the World Anti-Doping Agency (WADA) require methods of analysis that allow endogenous steroids to be distinguished from their synthetic analogs in urine. The ability to measure isotope distribution at natural abundance with high accuracy and precision has increased the application of Gas Chromatography,Combustion,Isotope Ratio Mass Spectrometry (GC,C,IRMS) to doping control in recent years. GC,C,IRMS is capable of measuring the carbon isotope ratio (,13C) of urinary steroids and confirm their synthetic origin based on the abnormal 13C content. This tutorial describes some of the complexities encountered by obtaining valid ,13C measurements from GC,C,IRMS and the need for careful interpretation of all relevant information concerning an individual's metabolism in order to make an informed decision with respect to a doping violation. Copyright © 2008 John Wiley & Sons, Ltd. [source] Book Review: Modern Practice of Gas Chromatography, 4th Edition.JOURNAL OF SEPARATION SCIENCE, JSS, Issue 15-16 2004E.F. Barry., Edited by: R.L. Grob [source] Comprehensive Two-Dimensional Gas Chromatography , GC×GCJOURNAL OF SEPARATION SCIENCE, JSS, Issue 5-6 2004Philip Marriott [source] Production of bioactive metabolites by Nocardia levis MK-VL_113LETTERS IN APPLIED MICROBIOLOGY, Issue 4 2009A. Kavitha Abstract Aims:, To isolate and identify the bioactive compounds produced by Nocardia levis MK-VL_113. Methods and Results:, Cultural characteristics of Noc. levis isolated from laterite soils of Guntur region were recorded on International Streptomyces Project media. Morphological studies of the strain through scanning electron microscopy revealed the clear pattern of its hyphal fragmentation into rod-shaped bacilli. Chemical examination of the secondary metabolites of the strain grown on sucrose,tryptone broth led to the isolation of three fractions active against Bacillus cereus. Further analysis of second fraction resulted in the isolation of two active subfractions. Two different phthalate esters, namely, bis-(2-ethylhexyl) phthalate and bis-(5-ethylheptyl) phthalate, were purified from the first active subfraction, and the structural elucidation of these compounds was confirmed on the basis of FT-IR, mass and NMR spectroscopy. The partially purified second subfraction subjected to Gas Chromatography,Mass spectroscopy contained nine components: decanedioic acid; 2,6-piperdione monooxime; 1-eicosanol; beta-1-arabinopyranoside, methyl; cyclopentaneundecanoic acid; hexadecanoic acid; silane, trichloro eicosyl; 1-hexacosanol; and 1,2-dodecanediol. The antimicrobial activity of the bioactive compounds produced by Noc. levis was expressed in terms of minimum inhibitory concentration. Conclusions:, The present study clearly revealed that the metabolites of Noc. levis act as bioactive compounds against Gram-positive and Gram-negative bacteria, yeast and filamentous fungi. It also supports the idea that there are a number of rare actinomycetes remained to be explored for new bioactive compounds. Significance and Impact of the Study:, Metabolites of Noc. levis exhibited antibacterial and antifungal activities. This is the first report of bis-(5-ethylheptyl) phthalate as well as the nine partially purified compounds from actinomycetes. In addition, this is also the first report of bis-(2-ethylhexyl) phthalate from the genus Nocardia. [source] Glass-Transition Temperature (Tg) of Free-Radically Prepared Polyacrylonitrile by Inverse Gas Chromatography, 1.MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 17 2002A Study on Tg of Atactic Monodisperse Polystyrenes Abstract The glass-transition temperature (Tg) of several atactic monodisperse polystyrenes (PSt)s was studied by an inverse gas chromatographic (IGC) analysis, as a preliminary study for the detection of the Tg of polyacrylonitrile. The Tg of PSt with different molecular weights was clearly obtained by this method. The agreement in the Tg values obtained by IGC and by differential scanning calorimetry (DSC) was quite good within the molecular-weight range Mp,=,7,600,2,430,000 (where, Mp,=,(Mn,×,Mw)1/2). This method has a wide universality for the detection of the Tg of polymers. Several essential factors were extracted for the establishment of the optimum conditions for IGC measurements, such as the concentration of polymer toward a clay matrix (10 wt.-%), and the type of lower probe, decane. The best probe was determined empirically from the most effective detection in the IGC measurements of PSt. Molecular-weight dependence of the Tg of PSt. Experimental data obtained here are indicated by an arrow. Other data was taken from ref.21 [source] Glass-Transition Temperature (Tg) of Free-Radically Prepared Polyacrylonitrile by Inverse Gas Chromatography, 2,.MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 17 2002Molecular-Weight Dependence of Tg of Two Different Types of Aqueous Polymers Abstract The molecular-weight dependence of the glass-transition temperature (Tg) of a series of atactic polyacrylonitriles (PAN)s was studied by inverse gas chromatographic (IGC) analysis. PANs having different molecular weights were prepared by either; (i) the addition of isopropyl alcohol as a chain-transfer agent, or (ii) a scission reaction induced by the addition of alkali (NaOH) to a solution (N,N -dimethylformamide solution, at 25,°C) of the resulting polymer. The intrinsic viscosity [,] was in the range of 10.9,0.1 (dl,·,g,1), which corresponds to a viscosity-averaged molecular weight (Mv) of 1,590,000,3,000. As part of the results, a side reaction, which saw the conversion of the nitrile (CN) groups of PAN into amide (CONH2) and/or carboxylic acids (COOH) groups by alkali, was found to occur. The typical molecular-weight dependence of the Tg in free-radically prepared PAN was discussed in connection with a chain-transfer mechanism in an aqueous medium. Molecular-weight dependence of the Tg for PAN (WA). An error bar is given by a short vertical arrow. [source] Quantitative Structure-retention Relationship for Gas Chromatography of Polychlorinated Naphthalenes by Ab initio Quantummechanical Calculations and a Cl Substitution Position MethodMOLECULAR INFORMATICS, Issue 1 2006Zhi-Cai Zhai Abstract Three quantitative structure-retention relationship (QSRR) models have been developed for gas chromatographic relative retention indices (RIs) of polychlorinated naphthalene (PCN) congeners. With computation at HF/6-31G* and B3LYP/6-31G* levels in Gaussian98 program, the structural parameters of PCNs were obtained and used as chemical descriptors to correlate with their gas chromatographic RIs by multiple linear regression analysis, resulting in model,1 and model,2. The squared correlation coefficients (r2) of the first two models are 0.9814 and 0.9957, and the cross-validation correlation coefficients (q2) are 0.9771 and 0.9948, respectively. On the other hand, the third model, model,3, was developed using the relative position of chlorine substitution as molecular descriptor, and its multiple squared correlation coefficient is r2,=,0.9967 and q2,=,0.9959, suggesting model,3 is practical and especially has a optimum predictive power. [source] Chiral Multidimensional Gas Chromatography (MDGC) and Chiral GC,Olfactometry with a Double-Cool-Strand Interface: Application to MalodorsCHEMISTRY & BIODIVERSITY, Issue 2 2006Frédéric Begnaud Abstract Volatile sulfur compounds such as 3-methyl-3-sulfanylhexan-1-ol (1) are largely responsible for axillary-sweat malodors. In this work, we describe the determination of the enantiomer ratio of the trace constituent 1 and the odor description of its antipodes (R)- and (S)- 1 by means of multidimensional gas chromatography (MDGC) in combination with chiral gas chromatography,olfactometry (GC-O). This technique allowed the on-line evaluation of the sensory character of both enantiomers via a sniffing port, and is based on a novel double-cool-strand interface (DCSI). First, the system's inertness was tested towards the labile compound 2-methylfuran-3-thiol (MFT; 2). Then, the DCSI was used in a new configuration to achieve olfactive characterization by means of chiral GC-O. In contrast to direct smelling after the chiral column, our technique allows, for the first time, to significantly delay the perception of the second-eluting enantiomer after the first one. This lowers the risk of sensory saturation, as the panelist can recover from the first stimulus, before evaluating the second one. To help programming the DCSI, a dedicated program was set up. The enantiomer ratio of the sweat malodor 1 was determined as (S)/(R) 3,:,1, and the dominating (S)-isomer was shown to largely impart its specific character to the overall odor of the sweat extract. [source] Cuticular hydrocarbons in workers of the slave-making ant Polyergus samurai and its slave, Formica japonica (Hymenoptera: Formicidae)ENTOMOLOGICAL SCIENCE, Issue 3 2003Zhibin LIU Abstract Comparisons of cuticular hydrocarbons between workers of the dulotic ant Polyergus samurai and its slave, Formica japonica, were carried out. Gas chromatography,mass spectrometry showed that the slave-maker and its slave shared the major cuticular hydrocarbon compounds, but possessed several minor products unique to each species. No difference in hydrocarbon composition was detected between enslaved and free-living F. japonica workers, suggesting that association with P. samurai has no qualitative effect on hydrocarbon composition in these ants. Principal component analyses of the cuticular hydrocarbon profiles (CHP) revealed that (i) CHP was species specific in a given mixed colony; and (ii) among mixed colonies, P. samurai workers had species-colony specific CHP, while the same feature was not always found in enslaved and free-living F. japonica workers. Therefore, a ,uniform colony odor' in terms of CHP is not achieved in naturally mixed colonies of P. samurai nor those of its slaves, F. japonica. [source] EVOLUTION OF REPRODUCTIVE STRATEGIES IN THE SEXUALLY DECEPTIVE ORCHID OPHRYS SPHEGODES: HOW DOES FLOWER-SPECIFIC VARIATION OF ODOR SIGNALS INFLUENCE REPRODUCTIVE SUCCESS?EVOLUTION, Issue 6 2000Manfred Ayasse Abstract The orchid Ophrys sphegodes Miller is pollinated by sexually excited males of the solitary bee Andrena nigroaenea, which are lured to the flowers by visual cues and volatile semiochemicals. In O. sphegodes, visits by pollinators are rare. Because of this low frequency of pollination, one would expect the evolution of strategies that increase the chance that males will visit more than one flower on the same plant; this would increase the number of pollination events on a plant and therefore the number of seeds produced. Using gas chromatography-mass spectrometry (GC-MS) analyses, we identified more than 100 compounds in the odor bouquets of labellum extracts from O. sphegodes; 24 compounds were found to be biologically active in male olfactory receptors based on gas chromatography with electroantennographic detection (GC-EAD). Gas chromatography (GC) analyses of odors from individual flowers showed less intraspecific variation in the odor bouquets of the biologically active compounds as compared to nonactive compounds. This can be explained by a higher selective pressure on the pollinator-attracting communication signal. Furthermore, we found a characteristic variation in the GC-EAD active esters and aldehydes among flowers of different stem positions within an inflorescence and in the n-alkanes and n-alkenes among plants from different populations. In our behavioral field tests, we showed that male bees learn the odor bouquets of individual flowers during mating attempts and recognize them in later encounters. Bees thereby avoid trying to mate with flowers they have visited previously, but do not avoid other flowers either of a different or the same plant. By varying the relative proportions of saturated esters and aldehydes between flowers of different stem positions, we demonstrated that a plant may take advantage of the learning abilities of the pollinators and influence flower visitation behavior. Sixty-seven percent of the males that visited one flower in an inflorescence returned to visit a second flower of the same inflorescence. However, geitonogamy is prevented and the likelihood of cross-fertilization is enhanced by the time required for the pollinium deposited on the pollinator to complete its bending movement, which is necessary for pollination to occur. Cross-fertilization is furthermore enhanced by the high degree of odor variation between plants. This variation minimizes learned avoidance of the flowers and increases the likelihood that a given pollinator would visit several to many different plants within a population. [source] Aroma-active compounds of American, French, Hungarian and Russian oak woods, studied by GC,MS and GC,OFLAVOUR AND FRAGRANCE JOURNAL, Issue 2 2008M. Consuelo Díaz-Maroto Abstract Gas chromatography,mass spectrometry (GC,MS) and gas chromatography,olfactometry (GC,O) were used to study aroma-active compounds in extracts of American, French, Hungarian and Russian oak woods. Compounds that presented high odour intensities for the non-toasted oak woods were guaiacol, hexanal, trans -2-nonenal, trans -oak lactone, cis- oak lactone, eugenol, vanillin and trans- isoeugenol, whilst the same compounds, in addition to furfural, 4-methylguaiacol and cis -isoeugenol, proved important in the toasted oaks. Like the oak lactones, cis- and trans- isoeugenol presented woody/oak odours, particularly in the toasted samples. For Hungarian and Russian samples, both characterized by their lower content of oak lactones, trans- and cis- isoeugenol presented higher odour intensities. For this reason, samples of low oak lactone concentrations, such as Hungarian and Russian oak woods, but also containing isoeugenols, can impart woody/oak odours to wines. Copyright © 2008 John Wiley & Sons, Ltd. [source] Characterization of the major odorants found in the peel oil of Citrus reticulata Blanco cv. Clementine using gas chromatography,olfactometryFLAVOUR AND FRAGRANCE JOURNAL, Issue 4 2003Mary G. Chisholm Abstract Gas chromatography,olfactometry (GC,O), gas chromatography,mass spectrometry (GC,MS) and preparative column chromatography were used to identify the key odorants present in laboratory-extracted clementine oil from Spain. Almost 50 odorants were identi,ed using GC,O, many of which were unsaturated aldehydes with high odour spectrum values (OSV). , - and , -sinensal, trans -4,5-epoxy-(E)-2-decanal, (E,Z)-2,6-dodecadienal and linalool were found to dominate clementine oil aroma. Enrichment of the oxygenates using preparative column chromatography provided further identi,cation of a total of 50 aldehydes, not all of which were present in the oil at concentrations high enough to produce a response using GC,O. Aldehydes contributed approximately 80% of the total aroma of clementine oil. New odorants not previously reported in clementine oil include many unsaturated aldehydes, trans -4,5-epoxy-(E)-2-decenal, trans -4,5-epoxy-(E)-2-dodecenal, 4-hydroxy-2,5-dimethyl-3(2H)-furanone (furaneol), 3-hydroxy-4,5-dimethyl-3(2H)-furanone (sotolon) and 1,8-cineole. No single odorant emerged as being characteristic of clementine oil aroma. Copyright © 2003 John Wiley & Sons, Ltd. [source] Identification de filtres solaires dérivés de l'acide para-aminobenzoique par spectroscopie RMN et par CPG/SMINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 5 2001M.-O. Masse Synopsis Gas chromatography coupled with mass spectrometry and protonic nuclear magnetic resonance used directly or on fractions obtained by preparative thin layer chromatography, allow identification of the main molecule in commercial samples of PABA (Cas RN 150-13-0), PEG-25 PABA (Cas RN 116242-27-4), glyceryl PABA (Cas RN136-44-7), ethyl dihydroxypropyl PABA (Cas RN 58882-17-0) or octyl dimethyl PABA (Cas RN 21245-02-3). Résumé La chromatographie en phase gazeuse couplée à la spectrométrie de masse et la résonance magnétique nucléaire protonique utilisée directement ou sur des fractions isolées par chromatographie sur couche mince préparative permettent d'identifier la molécule principale dans des échantillons commerciaux de PABA (Cas RN 150-13-0), PEG-25 PABA (Cas RN 116242-27-4), glyceryl PABA (Cas RN136-44-7), ethyl dihydroxypropyl PABA (Cas RN 58882-17-0) ou octyl dimethyl PABA (Cas RN 21245-02-3). [source] Approaching risk assessment of complex disease development in horse chestnut trees: a chemical ecologist's perspectiveJOURNAL OF APPLIED ENTOMOLOGY, Issue 5 2008A. B. Johne Abstract The chemo-ecological predispositions were investigated for the development of a complex disease on the basis of an insect,fungus mutualism using the system of horse chestnuts (Aesculus hippocastanum and Aesculus x carnea), the horse chestnut leaf miner (Cameraria ohridella) and the biotrophic powdery mildew (Erysiphe flexuosa). Both C. ohridella and E. flexuosa can appear on the same horse chestnut leaf tissue simultaneously. The olfactory detection of fungal infection by the insect, its ability to discriminate the potentially mutualistic fungus from other fungi and the impact of fungal infection on insect oviposition were examined. Gas chromatography coupled with mass spectroscopic and electroantennographic detection by C. ohridella (GC-MS/EAD) was used to assess the olfactory detection of fungal-infected A. hippocastanum and A. x carnea leaves by C. ohridella. Infection-related compounds, such as benzyl alcohol, dodecane, tridecane and methyl salicylate as well as fungus-related C8 compounds, are perceived by C. ohridella. The discrimination of E. flexuosa from another phytopathogenic fungus, such as Guignardia aesculi, is based primarily on the differing pattern of C8 compounds of these fungi. Oviposition on fungal-infected leaves of A. hippocastanum and leaves treated with fungal-related compounds showed that C. ohridella is able to respond to the modifications in the leaf volatile profiles of horse chestnuts caused by the different fungal infections. Thus, from the perception point of view, the necessary predispositions for the development of a close insect,fungus relation between the biotrophic fungus E. flexuosa and the leaf-mining insect C. ohridella are fulfilled. However, decreased oviposition on infected leaves does not enhance the selective contact between the species. As a consequence, an important predisposition for forming an insect,fungus mutualism is not fulfilled by these two species and, according to this approach, the risk of forming a complex disease can be assessed as low. [source] An oil-degrading bacterium: Rhodococcus erythropolis strain 3C-9 and its biosurfactantsJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2007F. Peng Abstract Aims:, To isolate a biosurfactant-producing bacterium and find new products within its culture. Methods and Results:, A biosurfactant-producing bacterium identified as Rhodococcus erythropolis (3C-9 strain) was isolated from seaside soil. When n -hexadecane was supplied as the sole carbon source, two types of biosurfactants (free fatty acids and glycolipids) were detected in the supernatant of the bacterial culture by use of thin layer chromatography (TLC). Gas chromatography,mass spectrometry (GC,MS) analysis revealed that the former consisted of at least 12 free fatty acids of chain lengths from C9 to C22; and the latter contained 2 kinds of glycolipids (a glucolipid and a trehalose lipid), which were detected by use of TLC, as well as GC,MS. The hydrophobic moieties of both glycolipids consisted of seven types of straight-chain fatty acids of varying compositions, with chain lengths ranging from C10 to C18. It was also noted that biosurfactants of strain 3C-9 were produced in a manner that was growth-related and cannot be synthesized from water-soluble substrates. The effects to enhance the solubility of polycyclic aromatic hydrocarbons and the degradation rate of hexadecane were also tested. Conclusions:, The biosurfactants produced by strain 3C-9 of R. erythropolis included two kinds of glycolipids, as well as free fatty acids. These biosurfactants were notably different from those of previously reported Rhodococcus species, both in terms of their structure and chemical composition. Significance and Impact of the Study:, Strain 3C-9 of R. erythropolis is a competitive candidate for use in oil spill cleanup operations, or in new biosurfactant exploration. The findings in this report show that Rhodococcus is a natural reservoir of new biosurfactants. [source] BIOCHEMICAL CHARACTERIZATION OF BORAGE (BORAGO OFFICINALIS L.) SEEDSJOURNAL OF FOOD BIOCHEMISTRY, Issue 3 2009BAYA MHAMDI ABSTRACT Gas chromatography,mass spectrometry analysis of seed Borago officinalis essential oil (EO) revealed the presence of 16 volatile components. ,-Caryophyllene (26%) and p-cymene-8-ol (19.7%) represented the major components, while nonadecane (0.7%) and hexanol (0.7%) were the minor ones. The EO composition was characterized by higher abundance of oxygenated monoterpenes (27.7%), followed by sesquiterpenes (26%). Fatty acid composition showed the predominance of linoleic (35.4%), oleic (24.2%) and ,-linolenic (20.4%) acids. Polyphenols were analyzed by reversed-phase high-performance liquid chromatography after acid hydrolysis of phenolic acid esters. Six phenolic acids were identified in seed extract and rosmarinic acid was the predominant one with 1.65 mg/g dry matter weight equivalent to 33% of total phenolic acids. PRACTICAL APPLICATIONS Borage (Borago officinalis L.) is of great interest because of its medicinal and nutritional properties. In fact, thanks to its characteristic composition in fatty acids, particularly high levels of gamma-linolenic acid in its seed oil, borage has gained importance. The potent consumers of this medicinal plant are hypertensive and hypercholesterolemic people. Borage consumption is also recommended for people suffering from rheumatism and eczema. Unfortunately, the knowledge about antioxidative/antiradical properties of borage is very scanty. So, recently, an extensive investigation was focused on the antioxidant properties of borage extracts. These extracts showed excellent antioxidant properties and their effects were attributed to their phenolic constituents. These antioxidants can be concentrated, either as crude extracts or individual phenolic compounds, to be used in highly unsaturated oils such as marine oils. Furthermore, borage consumption has been reported as a possible gastric cancer protective factor. [source] Methyl 3-[3,,4,-(methylenedioxy)phenyl]-2-methyl glycidate: An Ecstasy Precursor Seized in Sydney, AustraliaJOURNAL OF FORENSIC SCIENCES, Issue 4 2007Michael Collins Ph.D. Abstract:, Five 44 gallon drums labeled as glycidyl methacrylate were seized by the Australian Customs Service and the Australian Federal Police at Port Botany, Sydney, Australia, in December 2004. Each drum contained a white, semisolid substance that was initially suspected to be 3,4-methylenedioxymethylamphetamine (MDMA). Gas chromatography,mass spectroscopy (GC/MS) analysis demonstrated that the material was neither glycidyl methacrylate nor MDMA. Because intelligence sources employed by federal agents indicated that this material was in some way connected to MDMA production, suspicion fell on the various MDMA precursor chemicals. Using a number of techniques including proton nuclear magnetic resonance spectroscopy (1H NMR), carbon nuclear magnetic resonance spectroscopy (13C NMR), GC/MS, infrared spectroscopy, and total synthesis, the unknown substance was eventually identified as methyl 3-[3,,4,(methylenedioxy)phenyl]-2-methyl glycidate. The substance was also subjected to a published hydrolysis and decarboxylation procedure and gave a high yield of the MDMA precursor chemical, 3,4-methylenedioxyphenyl-2-propanone, thereby establishing this material as a "precursor to a precursor." [source] Gas chromatography,mass spectrometry analysis of endogenous cannabinoids in healthy and tumoral human brain and human cells in cultureJOURNAL OF NEUROCHEMISTRY, Issue 2 2001Mauro Maccarrone Endocannabinoids are lipid mediators thought to modulate central and peripheral neural functions. We report here gas chromatography,electron impact mass spectrometry analysis of human brain, showing that lipid extracts contain anandamide and 2-arachidonoylglycerol (2-AG), the most active endocannabinoids known to date. Human brain also contained the endocannabinoid-like compounds N -oleoylethanolamine, N -palmitoylethanolamine and N -stearoylethanolamine. Anandamide and 2-AG (0.16 ± 0.05 and 0.10 ± 0.05 nmol/mg protein, respectively) represented 7.7% and 4.8% of total endocannabinoid-like compounds, respectively. N -Palmitoyethanolamine was the most abundant (50%), followed by N -oleoyl (23.6%) and N -stearoyl (13.9%) ethanolamines. A similar composition in endocannabinoid-like compounds was found in human neuroblastoma CHP100 and lymphoma U937 cells, and also in rat brain. Remarkably, human meningioma specimens showed an approximately six-fold smaller content of all N -acylethanolamines, but not of 2-AG, and a similar decrease was observed in a human glioblastoma. These ex vivo results fully support the purported roles of endocannabinoids in the nervous system. [source] Phospholipid composition of articular cartilage boundary lubricantJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 4 2001A. V. Sarma The mechanism of lubrication in normal human joints depends on loading and velocity conditions. Boundary lubrication, a mechanism in which layers of molecules separate opposing surfaces, occurs under severe loading. This study was aimed at characterizing the phospholipid composition of the adsorbed molecular layer on the surface of normal cartilage that performs as a boundary lubricant. The different types of phospholipid adsorbed onto the surface of cartilage were isolated by extraction and identified by chromatography on silica gel paper and mass spectroscopy. The main phospholipid classes identified were quantified by a phosphate assay. Gas chromatography and electrospray ionization mass spectrometry were used to further characterize the fatty acyl chains in each major phospholipid component and to identify the molecular species present. Phosphatidylcholine (41%), phosphatidylethanolamine (27%) and sphingomyelin (32%) were the major components of the lipid layer on the normal cartilage surface. For each lipid type, a mixture of fatty acids was detected, with a higher percentage of unsaturated species compared to saturated species. The most abundant fatty acid observed with all three lipid types was oleic acid (C18:1). Additional work to further quantify the molecular species using electrospray ionization mass spectrometry is recommended. © 2001 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source] Alcohol-Induced Lipid and Morphological Changes in Chick Retinal DevelopmentALCOHOLISM, Issue 5 2004Yolanda Aguilera Abstract: Background: Alcohol exposure causes alterations in the lipid content of different organs and a reduction of long-chain fatty acids. During embryo development, the central nervous system is extremely vulnerable to the teratogenic effects of alcohol, and the visual system is particularly sensitive. Methods: White Leghorn chick embryos were injected with 10- and 20-,l alcohol doses into the yolk sac at day 6 of incubation. The lipid composition of the retina was analyzed in embryos at day 7 of incubation (E7), E11, E15, and E18. The percentages of phospholipids, free cholesterol, esterified cholesterol, diacylglycerides, and free fatty acids were estimated by using an Iatroscan thin layer chromatography flame ionization detector. Gas chromatography and mass spectrometry were used to determine fatty acid composition. The morphological study was performed at E7, E11, and E19 by means of semithin and immunohistochemical techniques. Results: In the retina, alcohol causes the total lipid content to change, with a remarkable increase in free cholesterol and a dramatic decrease in esterified cholesterol. Diacylglycerides and free fatty acids tend to increase. Phosphatidylcholine and phosphatidylethanolamine decrease, whereas phosphatidylserine, sphingomyelin, and phosphatidylinositol increase. The main fatty acids of the retina also undergo changes. At E7, myriotic acid increases, and oleic acid and polyunsaturated fatty acids such as arachidonic acid and docosahexaenoic acid decrease. From E18 onward, there is some recovery, except for fatty acids, which recover earlier. From a morphological point of view, alcohol effects on retinal development are various: increase of intercellular spaces in all cell layers, pyknosis with loss of cellularity in the inner nuclear cell layer and ganglion cell layer, retarded or disorderly cell migration, early cell differentiation, and loss of immunoreactivity for myelin oligodendrocyte,specific protein. Conclusions: Acute alcohol exposure during embryo development causes the lipid composition of the retina to change, with a trend to recovery in the last stages. These alterations are in line with the changes observed at a morphological level. [source] Chemical ecology of obligate pollination mutualisms: testing the ,private channel' hypothesis in the Breynia,Epicephala associationNEW PHYTOLOGIST, Issue 4 2010Glenn P. Svensson Summary ,Obligate mutualisms involving actively pollinating seed predators are among the most remarkable insect,plant relationships known, yet almost nothing is known about the chemistry of pollinator attraction in these systems. The extreme species specificity observed in these mutualisms may be maintained by specific chemical compounds through ,private channels'. Here, we tested this hypothesis using the monoecious Breynia vitis-idaea and its host-specific Epicephala pollinator as a model. ,Headspace samples were collected from both male and female flowers of the host. Gas chromatography with electroantennographic detection (GC-EAD), coupled gas chromatography,mass spectrometry, and olfactometer bioassays were used to identify the floral compounds acting as the pollinator attractant. ,Male and female flowers of B. vitis-idaea produced similar sets of general floral compounds, but in different ratios, and male flowers emitted significantly more scent than female flowers. A mixture of 2-phenylethyl alcohol and 2-phenylacetonitrile, the two most abundant compounds in male flowers, was as attractive to female moths as the male flower sample, although the individual compounds were slightly less attractive when tested separately. ,Data on the floral scent signals mediating obligate mutualisms involving active pollination are still very limited. We show that system-specific chemistry is not necessary for efficient host location by exclusive pollinators in these tightly coevolved mutualisms. [source] GC,MS characterization of oligomers in polyadipates used as plasticizers for PVC in food contactPACKAGING TECHNOLOGY AND SCIENCE, Issue 3 2006Maurus Biedermann Abstract Fourteen commercial polyadipates and a polysebacate were analysed for their components of a molecular mass below 1000,Da, primarily with the aim of generating the background data for measuring the migration of this type of polymeric additives from plasticized PVC (e.g. cling films and gaskets of lids) into foods or food simulants. Since the composition of the material <1000,Da varies between the polyadipates, the main components must be identified to enable a correct quantification. Polyadipates differ in the diol used as linker, their termination (acid or alcohol) and in the end-capping (free alcohols, acetylation, acylation with fatty acids, esterification with octanol/decanol). Gas chromatography (GC) provides good separation, but the material remaining in the column up to high temperatures decomposes and forms a hump in the rear part of the chromatogram. Examples of mass spectra are shown, the most indicative fragments pointed out and spectra of 159 components listed. The polyadipates and the sebacate are characterized by their structure, the main components <1000,Da and the fraction of material <1000,Da. Copyright © 2006 John Wiley & Sons, Ltd. [source] Overexpression of the apple alcohol acyltransferase gene alters the profile of volatile blends in transgenic tobacco leavesPHYSIOLOGIA PLANTARUM, Issue 3 2008Dapeng Li Alcohol acyltransferases (AATs) are key enzymes in ester biosynthesis. Previous studies have found that AAT may be a stress-related gene. To investigate further the function of the apple alcohol acyltransferase gene (MdAAT2), transgenic tobacco plants overexpressing MdAAT2 were generated. Gas chromatography,mass spectroscopy analysis showed that the volatile blends were altered in these transgenic tobacco leaves. Although no apple-fruity volatile esters were detected in transgenic tobacco leaves, methyl caprylate, methyl caprate, and methyl dodecanoate were newly generated, and the concentrations of methyl benzoate and methyl tetradecanoate were significantly increased, suggesting that MdAAT2 may use medium-chain fatty acyl CoA and benzoyl-CoA as acyl donors together with methanol acceptors as substrates. Surprisingly, the concentrations of linalool were significantly increased in transgenic tobacco leaves, which may mediate the repellent effect on Myzus persicae (Sulzer) aphids. Using methyl jasmonate (MeJA) and wounding treatments, we found that MdAAT2 may substitute for the partial ability of MeJA to induce the production of linalool in transgenic plants. These data suggest that MdAAT2 may be involved in the response to the MeJA signal and may play a role in the response to biotic and abiotic stress. [source] Gas chromatography,mass spectrometry analyses of volatile organic compounds from potato tubers inoculated with Phytophthora infestans or Fusarium coeruleumPLANT PATHOLOGY, Issue 4 2001B. P. J. De Lacy Costello Volatile organic compounds (VOCs) collected from potato tubers inoculated with Phytophthora infestans (late blight), Fusarium coeruleum (dry rot) or sterilized distilled water (as a control) were analysed using gas chromatography,mass spectrometry (GC,MS) and gas chromatography,flame ionization detection (GC,FID). A total of 52 volatiles were identified by GC,MS in the headspaces above P. infestans- and F. coeruleum- inoculated tubers after incubation for 42 days in the dark at 10°C. Of these VOCs, the six most abundant were common to both pathogens. These were benzothiazole (highest abundance), 2-ethyl-1-hexanol (second highest abundance), and at approximately equal third abundance, hexanal, 2-methylpropanoic acid-2,2-dimethyl-1-(2-hydroxy-1-methylethyl)-propyl ester, 2-methylpropanoic acid-3-hydroxy-2,4,4-trimethyl-pentyl ester and phenol. In addition, styrene also occurred at approximately equal third abundance in the headspace of F. coeruleum- inoculated tubers, but at lower abundance in the headspace of P. infestans- inoculated tubers. Some VOCs were specific to each pathogen. Butanal, 3-methylbutanal, undecane and verbenone were found at low levels only in the headspace of tubers inoculated with P. infestans, while 2-pentylfuran and copaene were found only in the headspace of tubers inoculated with F. coeruleum. Additionally GC,FID analysis identified ethanol and 2-propanol in the liquid exudate from both P. infestans - and F. coeruleum -inoculated tubers after incubation for 35 days, and in the headspace after incubation for 42 days. These data provide key information for developing a sensor-based early warning system for the detection of postharvest diseases in stored potato tubers. [source] Gas chromatography coupled to electron capture negative ion mass spectrometry with nitrogen as the reagent gas , an alternative method for the determination of polybrominated compoundsRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 23 2009Natalie Rosenfelder Gas chromatography in combination with electron capture negative ion mass spectrometry (GC/ECNI-MS) is a sensitive method for the determination of polybrominated compounds in environmental and food samples via detection of the bromide ion isotopes m/z 79 and 81. The standard reagent gas for inducing chemical ionization in GC/ECNI-MS is methane. However, the use of methane has some drawbacks as it promotes carbonization of the filament and ion source. In this study, we explored the suitability of nitrogen as reagent gas for the determination of brominated flame retardants (polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs), allyl-2,4,6-tribromophenyl ether (ATE) and 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE)) and halogenated natural products (for instance, methoxylated tetrabrominated diphenylethers and polybrominated hexahydroxanthene derivatives). An ion source temperature of 250°C and a nitrogen pressure of 7 Torr in the ion source gave the highest response for m/z 79 and 81 of virtually all investigated polybrominated compounds. Using these conditions, nitrogen-mediated GC/ECNI-MS usually gave higher sensitivity than the method with methane previously used in our lab. In addition, the ion source was not contaminated to the same degree and the lifetime of the filament was significantly increased. Moreover, the response factors of the different polybrominated compounds with the exception of 2,4,6-tribromophenol were more uniform than with methane. Nitrogen is available at very high purity at relatively low price. Copyright © 2009 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||||||||||||||||||||||||||