Search results for "Gas Chromatography"
showing 10 items of 750 documents
Identification and quantitation of trace amounts of barbiturates with glass capillary gas chromatography
1979
Pre-chromatographic reactions are no longer a necessary evil. Equipment such as the microrefluxer now allows reproducible 7-μl-reactions to be carried out in a short time. Thus multiple derivatisations can be used together with glass capillary GC for routine identifications. The method has been succesfully applied to barbiturates. Retention data of their methyl-, allyl- and benzyl-derivatives are given. Quantitative blood level determinations are briefly discussed.
Sorption of 4-ethylphenol and 4-ethylguaiacol by suberin from cork
2015
International audience; Cork shows an active role in the sorption of volatile phenols from wine. The sorption properties of 4-ethylphenol and 4-ethylguaiacol phenols in hydro-alcoholic medium placed in contact with suberin extracted from cork were especially investigated. To that purpose, suberin was immersed in model wine solutions containing several concentrations of each phenol and the amount of the compound remaining in the liquid phase was determined by SPME-GC-MS. Sorption isotherms of 4-ethylguaiacol and 4-ethylphenol by suberin followed the Henry's model. The solid/liquid partition coefficients (KSL) between the suberin and the model wine were also determined for several other volat…
Production of volatile compounds in liquid cultures by six strains of coryneform bacteria
1992
The aromatic profiles of four strains of Brevibacterium linens, one strain of Brevibacterium sp. and one strain of Microbacterium sp. were determined with some pure cultures of these microorganisms in standard trypcase soy liquid medium, which enabled four of these six strains to produce flavour compounds of ripened cheese. Thirty-two flavour compounds were identified by gas chromatography and mass spectrometry. The identified flavour compounds included the following: fatty acids, alcohols, methylketones, sulphur compounds, aromatic compounds and a pyrazine. Some important differences were found among the six strains studied. The four strains of B. linens had similar flavour profiles. Their…
A denuder-impinger system with in situ derivatization followed by gas chromatography-mass spectrometry for the determination of gaseous iodine-contai…
2008
Reactive iodine species have been suggested to play an important role in the atmosphere (e.g. tropospheric ozone depletion, coastal new particle formation). However, there still exist major uncertainties about their atmospheric chemistry, mostly due to the lack of analytical approaches for the accurate speciation of certain key compounds. In this study, 1,3,5-trimethoxybenzene (1,3,5-TMB)-coated denuder proved to be suitable for the differentiation between gaseous interhalogens (iodine monochloride (ICl), iodine monobromide (IBr)) and molecular iodine (I2) based on a selective collection/derivatization method. The results of the denuder sampling were compared with the results of impinger sa…
Investigation of sterols as potential biomarkers for the detection of pig (S. s. domesticus) decomposition fluid in soils
2012
This study was carried out to evaluate the potential of using cholesterol and coprostanol, as indicators for the detection of decomposition fluid of buried pigs (S. s. domesticus) in soils. In May 2007, four pig carcasses (~35. kg) were buried in shallow graves (~40. cm depth) at the University of Ontario Institute of Technology in Canada. Two pigs were exhumed after three months (Pig 1, Pig 2) and six months (Pig 3, Pig 4) post burial. Soil samples were collected beneath the pig carcasses (~40. cm depth) and from grave walls (~15-20. cm depth) as well as from a parallel control site. Coprostanol and cholesterol were extracted from soils, purified with solid phase extraction (SPE) and analy…
Bioactive compounds from mustard flours for the control of patulin production in wheat tortillas
2016
Abstract Patulin (PAT) is a toxic fungal metabolite produced by Penicillium, Aspergillus and Byssochlamys growing especially in fruit and cereals. PAT exhibits a number of toxic effects in animals and its presence in food is undesirable. In this study the reduction of the mycotoxin PAT produced by a strain of Penicillium expansum, on wheat tortillas was studied using volatile bioactive compounds present in the oriental and yellow mustard flour and also using the standard solution of the antifungal compound allyl isothiocyanate (AIT), developing an active packaging with two different systems of release of those bioactive compounds. Also the kinetic of volatilization of the compounds used in …
Photoreduction of carbon dioxide to formic acid in aqueous suspension: a comparison between phthalocyanine/TiO2 and porphyrin/TiO2 catalysed processes
2014
Composite materials prepared by loading polycrystalline TiO2 powders with lipophilic highly branched Cu(II)- and metal-free phthalocyanines or porphyrins, which have been used in the past as photocatalysts for photodegradative processes, have been successfully tested for the efficient photoreduction of carbon dioxide in aqueous suspension affording significant amounts of formic acid. The results indicated that the presence of the sensitizers is beneficial for the photoactivity, confirming the important role of Cu(II) co-ordinated in the middle of the macrocycles. A comparison between Cu(II) phthalocyanines and Cu(II) porphyrins indicated that the Cu(II)- phthalocyanine sensitizer was more e…
Production of methylated mercury, lead, and cadmium by marine bacteria as a significant natural source for atmospheric heavy metals in polar regions
1999
Abstract Mixed and pure bacterial cultures of polar origin were incubated in model experiments under polar conditions. The releasing rates of monomethyl and dimethyl mercury (MeHg+ and Me2Hg), trimethyl lead (Me3Pb+), and monomethyl cadmium (MeCd+) were determined in dependence on the incubation time. This is the first time that methylation of cadmium by bacteria could be shown. The formation of tetramethyl and dimethyl lead (Me4Pb and Me2Pb2+) was also checked but no release of these methylated compounds was observed. The determination of methylated mercury compounds was carried out by using a purge and trap system after derivatisation of monomethyl mercury into the volatile methylethyl me…
Laurus nobilis L. Seed Extract Reveals Collateral Sensitivity in Multidrug-Resistant P-Glycoprotein-Expressing Tumor Cells.
2015
The frequent failure of standard cancer chemotherapy requires the development of novel drugs capable of killing otherwise drug-resistant tumors. Here, we have investigated a chloroform extract of Laurus nobilis seeds. Fatty acids and 23 constituents of the volatile fraction were identified by gas chromotography/flame ionization detection (GC/FID) and gas chromatography/mass spectrometry (GC/MS), in good agreement with (1)H NMR (nuclear magnetic resonance) spectrum. Multidrug-resistant P-glycoprotein-expressing CEM/ADR5000 leukemia cells were hypersensitive (collaterally sensitive) toward this extract compared to drug-sensitive CCRF-CEM cells, whereas CEM/ADR5000 cells were 2586-fold resista…
Gas—liquid chromatographic analyses
1984
Abstract The gas chromatography (GC) of n -alkyl acetates (CH 3 COOR), chloroacetates (CH 2 ClCOOR), dichloroacetates (CHCl 2 COOR) and trichloroacetates (CCl 3 COOR), where the alcohol chain length (R) varied between 1 and 8, and certain of their monochlorinated derivatives, 176 compounds altogether, has been studied on SE-30 and OV-351 glass capillary columns under the same operating conditions. The isomeric monochlorinated esters are eluted in direct order from the 1- chloro to the ω-chloro isomer, the separation of the isomers being complete on OV- 351. On SE-30, however, the peaks of the 6- and 7-chlorooctyl esters are partly overlapped. The separation of the mixtures of odd- and e…