Search results for "gas chromatography."
showing 10 items of 725 documents
TASCAを用いたCn, Nh, Fl化学実験のためのHg, Tl, PbのSiO2及びAu表面に対するオンライン化学吸着研究
2018
Online gas-solid adsorption studies with single atom quantities of Hg, Tl, and Pb on SiO$_{2}$ and Au surfaces were carried out using short-lived radioisotopes with half-lives in the range of 4-49 s. This is a model study to measure adsorption enthalpies of superheavy elements Cn, Nh, and Fl. The short-lived isotopes were produced and separated by the gas-filled recoil separator TASCA at GSI. The products were stopped in He gas, and flushed into gas chromatography columns made of Si detectors whose surfaces were covered by SiO$_{2}$ or Au. The short-lived Tl and Pb were successfully measured by the Si detectors with the SiO$_{2}$ surface at room temperature. On the other hand, the Hg did no…
Changes in Terpene Content in Milk from Pasture-Fed Cows
2006
Changes of terpene content in milk from cows grazing natural diversified upland pasture were examined in this observational trial. A homogeneous plot divided into 2 subplots was used from May 31 to July 1, 2003 (first growth) and again from October 1 to October 7, 2003 (vegetative regrowth). Each subplot was grazed by 6 dairy cows in 2 ways: strip grazing (SG), with new allocations of pasture strips at 2-d intervals, and paddock grazing (PG). The PG subplot was divided into 3 paddocks and the cows were moved to a new paddock on June 13 and June 24, 2003. Milk from the 6 cows was collected twice a week, pooled, and used for terpene analyses by dynamic headspace gas chromatography-mass spectr…
Investigation on the influence of spray-drying technology on the quality of Sicilian Nero d’Avola wines
2018
The purpose of the present work was to find a correlation between microencapsulation technology applied to wines and the resulting quality of the wine itself in terms of volatile composition and phenolic profile. To this aim, samples of Nero d'Avola wines produced in Sicily (Italy) were investigated in order to: i) elucidate the aromatic composition by means of HSâSPME coupled with GCâMS; ii) assess the polyphenolic content by UHPLC mass spectrometry; iii) compare the results obtained from both the screenings with those relative to the same wines that had previously been subjected to spray-drying. The results showed a marked reductionThe results here obtained evidenced a marked reductio…
Anti-Pseudomonas aeruginosa activity of hemlock (Conium maculatum, Apiaceae) essential oil
2018
Conium maculatum is a nitrophilous weed belonging to the Apiaceae family and occurring in hedgerows, pastures, waste ground, along rivers and roadsides. Little is known on the chemistry and bioactivity of other secondary metabolites occurring in the plant. In the present work, we have analysed the chemical composition and antimicrobial activity of the essential oils hydrodistilled from leaves and inflorescenes of C. maculatum growing in Sicily, Italy. The composition of essential oils was achieved by gas chromatography-mass spectrometry (GC-MS) analysis, whereas the inhibitory effects on the growth of two Gram negative strains, namely Escherichia coli and Pseudomonas aeruginosa were assesse…
Chemical composition of the essential oil from Thapsia garganica L. (Apiaceae) grown wild in Sicily and its antimicrobial activity.
2015
In this study, the chemical composition of the essential oil from flowers and leaves of Thapsia garganica L. collected in Sicily was evaluated by GC and GC-MS. The main components of T. garganica flower oil (T.f.) were chamazulene (58.3%), humulene oxide II (9.0%), tricosane (8.2%) and pentacosane (8.2%). Also the oil from leaves (T.l.) was characterised by high content of chamazulene (49.2%). Other abundant metabolites were 1,4-dimethylazulene (18.5%), (E)-phytol (6.3%) and neophytadiene (5.1%). The comparison with other studied oils of genus Thapsia is discussed. Antimicrobial activity against several micro-organisms, including some ones infesting historical art craft, was also determined.
Chemical composition of essential oils of Anthemis secundiramea Biv. subsp. secundiramea (Asteraceae) collected wild in Sicily and their activity on …
2016
In the present study, the chemical composition of the essential oil from the aerial parts of Anthemis secundiramea Biv. subsp. secundiramea L. collected in Sicily was evaluated by GC and gas chromatography–mass spectrometry. The main components of A. secundiramea were (Z)-lyratyl acetate (14.6%), (Z)-chrysanthenyl acetate (9.9%), (Z)-chrysanthenol (8.7%) and (E)-chrysanthenyl acetate (7.7%). The comparing with other studied oils of genus Anthemis belonging to the same clade is discussed. Antibacterial and antifungal activities against some micro-organisms infesting historical art craft, were also determined.
Bioactivity of essential oils in phytopathogenic and post-harvest fungi control
2017
[EN] Commercial thyme and lavender essential oils were analysed by GC/MS. Sixty-six compounds accounting for 98.6¿99.6% of total essential oil were identified. Thymol (52.14 ± 0.21%), followed by pcymene (32.24 ± 0.16%), carvacrol (3.71 ± 0.01%) and ¿-terpinene (3.34 ± 0.02%), were the main compounds in thyme essential oil, while large amounts of oxygenated monoterpenes linalool acetate (37.07 ± 0.24%) and linalool (30.16 ± 0.06%) were found in lavender one. In vitro antifungal activity of the essential oils was evaluated at 200 and 300 ¿g/mL against 10 phytopathogenic and post-harvest fungi, which significantly affect agriculture. Micelial growth inhibition was calculated for each tested f…
Gas-liquid chromatographic analyses
1983
Abstract The gas chromatography of mixtures of n -alkyl acetates (CH 3 COOR, R = C 1 —C 8 ) and methyl esters of aliphatic n -carboxylic acids (R′COOCH 3 , R′ = C 1 —C 8 ) and certain of their monochlorinated derivatives has been studied on Carbowax 20M and SE-30 glass capillary columns under the same operating conditions. The separation of the isomeric monochlorinated esters was complete on Carbowax 20M, whereas on SE-30 the peaks of 6- and 7-chlorooctyl acetates and methyl (ω − 1)- and (ω − 2)-chlorooctanoates and -nonanoates partly overlapped. The complete separation of the mixtures could not be achieved, however, on Carbowax 20M, in spite of the use of various operating conditions. The …
Characterisation of humic substances by acid catalysed transesterification
2002
Abstract The chemical composition of low molecular weight moieties linked to the core structures of humic substances (HS) are of substantial importance for the understanding of the chemical structures and mode of interactions of HS with other substances in the environment. In this study a novel approach to characterise certain low molecular weight compounds bound to HS is suggested. The method includes transesterification (TE) of ester and amide bound structures, and esterification (E) of free carboxylic groups using acid catalysed methanolysis followed by gas chromatography (GC)–mass spectrometry (MS) and GC-FID analysis. Methanolysis of five HS of different origin, demonstrated the presen…
Gas assisted mechanical expression (GAME) for the selective recovery of lipophilic and hydrophilic compounds from olive kernel
2017
Abstract This work is devoted to valorize olive kernel; a by-product produced during olive oil extraction process. For this purpose, aqueous liquid solid extraction (LSE), mechanical expression (ME), supercritical CO2 (SC-CO2) and gas assisted mechanical expression (GAME), processes were compared when applied separately or consequently (ME + GAME), in terms of total phenolic compound (TPC) and oil recovery yields. Results showed that although the high extraction yields of TPC using LSE (61.4 ± 1.3%), the extraction process is economically not viable. However, it was demonstrated that applying ME (1 h at 30 MPa) followed by GAME (1 h at 30 MPa ME and 10 MPa SC-CO2 pressures) allowed recoveri…