Search results for "Gas Chromatography"
showing 10 items of 750 documents
CHEMICAL AND PHYSICAL SIGNALS MEDIATING CONSPECIFIC AND HETEROSPECIFIC AGGREGATION BEHAVIOR OF FIRST INSTAR STINK BUGS
2004
We investigated cues that mediate the aggregation behavior of immature pentatomid bugs by using nymphs of six different pentatomid bug species (Nezara viridula, Acrosternum hilare, Chlorochroa ligata, Chlorochroa sayi, Thyanta pallidovirens, and Euschistus conspersus). When first instars of any two species were put together in a Petri dish, they readily formed heterospecific aggregations similar to their natural conspecific aggregations. The chemical profiles of first and second instar nymphs of each species were determined by solvent extraction with pentane, followed by GC-MS analysis. Immature bugs of the different species had some compounds in common, and some that were more species spec…
Retention-release equilibrium of aroma compounds in polysaccharide gels: study by quantitative structure-activity/property relationships approach
2010
The nature and amount of constituents in food greatly influence aroma release. Pectins and carrageenans are common used thickeners, but their effect on the release of aroma compounds has been studied more frequently for non- homogeneous products than for thickeners separately. The purpose of this work was to study and compare their respective effects in simple model systems. In this way, the release of 13 aroma compounds was analysed by headspace analysis at equilibrium in pure water, i-carrageenan and pectin gels. To evaluate the influence of the chemical structure of aroma com- pounds on retention/release equilibrium between vapour phase and gels, we used a quantitative structure-activity…
A new approach to studying sponge cake aroma after storage in treated paper and plastic packaging by direct gas chromatography–olfactometry (D-GC–O)
2007
The objective of this study was to use D-GC–O to compare the global odour of a sponge cake flavoured with either a ‘viennoiserie’ aromatic note or a simplified mixture of aroma compounds (used for physicochemical studies), then stored in a glass packaging (inert and impermeable) or in pouches made with treated papers or with plastic packaging, in accelerated ageing conditions (high temperature and relative humidity gradient). After 1 week of storage, the flavoured sponge cake headspace was SPME-extracted directly into the packaging and analysed by D-GC–O. The sponge cake global odour was better retained if plastic film rather than treated-papers was used, for both flavourings. Changes in th…
A passive sampling-based analytical strategy for the determination of volatile organic compounds in the air of working areas.
2010
Abstract An analytical methodology based on the use of a polyethylene layflat tube filled with activated carbon and Florisil (ACFL-VERAM) was employed for the passive sampling of volatile organic compounds (VOCs) in the air of working areas of packing industries. VOCs amount in the ACFL-VERAM sampler was directly determined through head-space-gas chromatography–mass spectrometry (HS-GC–MS) allowing a direct determination in only 20 min without the need of any previous treatment. Uptake parameters, like sampling rate ( R S ) and sampler–air partition coefficient ( K SA ), were determined for every studied VOC from adsorption isotherm data. Additionally, experimental equations have been propo…
Gaining deeper insight into aroma perception: An integrative study of the oral processing of breads with different structures
2017
WOS:000394071900015; International audience; The objective of this study was to investigate for the first time the influence of bread structure, volatile compounds, and oral processing on aroma perception. 3 types of French baguette were created using the same raw ingredients but different bread-making processes; they consequently varied in their crumb and crust structures. We characterized the initial volatile profiles of two bread structural subtypes-namely bread crumb and bread crumb with crust-using proton transfer reaction-mass spectrometry (PTR-MS) headspace analysis. Three types of bread were characterized by thirty-nine ion fragments from m/z 45 to 139. We then conducted a study in …
Effects of water on gas chromatographic column efficiency measurements applied to on-column injections of volatile aroma compounds
2002
International audience
Breath testing as a method for detecting lung cancer
2014
Early diagnosis of lung cancer is important due to high mortality in late stages of the disease. An ideal approach for population screening could be the breath analysis, due to its non-invasiveness, simplicity and cheapness. Using sensitive methods of analysis like gas chromatography/mass spectrometry in exhaled air of cancer patients were discovered some volatile organic compounds - possible candidates for cancer markers. However, these compounds were not specific for cancer cells. At the same time, integrative approaches used to analyze the exhaled breath have demonstrated high sensitivity and specificity of this method for lung cancer diagnosis. Such integrative approaches include detect…
Identification of organic compounds in fictile unguentaria from two Sicilian necropolis of Greek age (5th century, b.c.) by GC-MS analysis.
2007
A study to obtain more knowledge on funeral set in Greek age, (5th Century, b.C.) was carried out on thirteen ancient unguentaria, small vessels used as containers of balms or ointments, founded in two different Sicilian necropolis: Adranon and Hymera. Every find was subjected to three extractions by increasing polarity solvents. All crude extracts, unsaponifiables and methyl esters of saponifiable fraction were analysed by GC-MS. Analysis showed difference between two groups of finds: the unguentaria from Adranon show abundant traces of lipids used in balm making, while those from Hymera resulted empty and buried for ritual purpose. Even if in the two towns, flourished in the same period, …
Comparison of stir bar sorptive extraction in the liquid and vapour phases, solvent-assisted flavour evaporation and headspace solid-phase microextra…
2017
The volatile fraction plays an important role on the organoleptic properties and overall acceptability of fruit juices. This work reports for first time a non-targeted approach for the analysis of the volatile fraction of fruit juice by stir bar sorptive extraction (SBSE[1]) in liquid and vapour phase (HSSE[2]) at three extraction times (30, 60, and 120 min), two temperatures (room temperature and 40 °C), and two sample volumes (5 and 10 mL). The resultant volatile profiles were compared with solvent-assisted flavour evaporation (SAFE[3]) and headspace solid-phase microextraction (HS-SPME[4]). SBSE and HSSE enabled the detection and identification of more compounds than HS-SPME and less tha…
Rapid and direct gas chromatographic determination of oxalic acid in urine
1979
The known methods of oxalic acid determination are not suitable for reliable, rapid and economical routine analysis. A rapid gas chromatographic method has been developed which dispenses with separation operations and measures oxalic acid as a diethylester by means of back-flushing, and using malonic acid as an internal standard. One determination can be conducted within 6 to 8 min. and preparation of the specimen takes about the same amount of time. If the gas chromatographic conditions are changed and more time is permitted for analysis, numerous other extractable acidic metabolites can also be determined.