Search results for "Gas Chromatography"

Effects of heat treatment and acid-induced gelation on aroma release from flavoured skim milk

2010

Abstract Time dependent aroma release was studied in skim milk, heated skim milk as well as in acid-induced gels derived from them using static headspace – gas chromatography analysis. A variable order kinetic model was fitted to experimental data and was used to determine headspace equilibrium concentration and initial rates of release. When compared to water, retention in milk based matrices was increased for hydrophobic aroma compounds, while it was decreased for more hydrophilic volatiles. Acid gelation reduced the initial rate of aroma release by a factor varying from 2.0 to 3.8, depending on the compound. Positive deviation from the first order kinetics was observed and suggests that …

Ageing behaviour and analytical characterization of the Jatobá resin collected from Hymenaea stigonocarpa Mart.

2009

Abstract This paper reports the results of an analytical study to characterize the trunk resin collected from the Hymenaea stigonocarpa Mart. species from the region of Minas Gerais (Brazil), popularly known as Jatoba resin. Hymenaea resins are reported to have been used in artistic applications such as protective varnishes in polychromed sculptures and paintings. Therefore, the identification of the main chemical changes that take place in the resin when it is prepared as a thin film exposed to atmospheric effects have been considered herein. Changes due to the degradation effect of light have been studied on a series of specimens prepared as a thin films and subjected to accelerated UV li…

Chemical variability in the essential oil of Cinnamomum tamala L. leaves from India.

2011

The chemical composition of the essential oils obtained from the fresh leaves of Cinnamomum tamala Nees et Eberm. was determined by GC and GC–MS. The yield of the oil on a dry weight basis ranged from 1.2% to 3.9% (w/w). Phenyl propanoids constitute the major portion (88.9–95.0%) of the oils. Fifty-four compounds were identified from the oils. Eugenol (91.4–41.8%) was the main compound, followed by eugenyl acetate (0.0–47.1%) and α-phellandrene (0.6–2.5%) in the analysed oils.

Involvement of an Alkane Hydroxylase System of Gordonia sp. Strain SoCg in Degradation of Solid n-Alkanes▿

2010

ABSTRACT Enzymes involved in oxidation of long-chain n -alkanes are still not well known, especially those in Gram-positive bacteria. This work describes the alkane degradation system of the n -alkane degrader actinobacterium Gordonia sp. strain SoCg, which is able to grow on n -alkanes from dodecane (C 12 ) to hexatriacontane (C 36 ) as the sole C source. SoCg harbors in its chromosome a single alk locus carrying six open reading frames (ORFs), which shows 78 to 79% identity with the alkane hydroxylase (AH)-encoding systems of other alkane-degrading actinobacteria. Quantitative reverse transcription-PCR showed that the genes encoding AlkB (alkane 1-monooxygenase), RubA3 (rubredoxin), RubA4…

Isolation of Gram-positive n-alkane degraders from a hydrocarbon-contaminated Mediterranean shoreline.

2007

Aims: To investigate the petroleum hydrocarbon (HC)-degrading potential of indigenous micro-organisms in a sandy Mediterranean coast, accidentally contaminated with petroleum-derived HCs. Methods and Results: Using culturable methods, a population of Gram-positive n-alkane degraders was detected in the contaminated soil. Five isolates, identified as one Nocardia, two Rhodococcus and two Gordonia strains, were able to degrade medium- and long-chain n-alkanes up to C36 as assessed by growth assays and gas chromatography-mass spectrometry analysis. Diverging alkane hydroxylase-encoding genes (alkB) were detected by PCR, using degenerated primers, in all the strains; multiple sequences were obt…

Agronomical and chemical characterisation of Thymbra capitata (L.) Cav. biotypes from Sicily, Italy

2015

In this study the agromomical and chemical characterization of 13 sicilian biotypes of Thymbra capitata (L.) Cav. (or Thymus capitatus Hoff. et Link.) collected from different areas of Sicily (Italy) and grown under the same agricultural and environmental condition are reported. The main morpho-productive parameters and quali-quantitative profile of essential oils were determined . Essential oils were extracts from the aerial parts of the plants by hydrodistillation. The essential oils were analyzed by GC-FID and GC-MS. Hierarchical Cluster Analysis and Principal Component Analysis statistical methods were used to group biotypes according to the essential oils chemical composition. The esse…

Gas chromatography/mass spectrometry characterization of historical varnishes of ancient Italian lutes and violin

2007

The organic constituents of historical vanishes from two ancient Italian lutes and a Stradivari violin, kept in the Musée de la musique in Paris, have been characterized using gas chromatography-mass spectrometry. Results have been compared with the chromatograms and mass spectra of recent as well as old naturally aged reference materials. The three historical varnishes analyzed have been shown to be oil varnishes, probably mixtures of linseed oil with resins. Identification of diterpenoids and triterpenoids compounds, and of the resins that may have been ingredients of the varnishes, are discussed in this paper.

Volatile flavour components of ocimum basilicum var. hispidum (lam.) Chiov.

1991

The volatile components obtained by steam-distillation ofOcimum basilicum var. hispidum (Lam.) Chiov. (Labiatae) were analysed by gas chromatography (GC) and gas chromatography—mass spectrometry (GC-MS). A total of 21 compounds, representing ca 90% of the total oil, were identified. The identity of the main component (82%), dihydrotagetone, was confirmed by 1H- and 13C-NMR spectroscopy. This is the first report of this compound in the genus Ocimum.

A fast extraction procedure of 2-dodecylcyclobutanone for the identification of irradiated pork, employing gas chromatographic/mass spectrometric ana…

2008

Determination of 60 Migrant Substances in Plastic Food Contact Materials by Vortex-Assisted Liquid-Liquid Extraction and GC-Q-Orbitrap HRMS

2021

A GC-HRMS analytical method for the determination of 60 migrant substances, including aldehydes, ketones, phthalates and other plasticizers, phenol derivatives, acrylates, and methacrylates, in plastic food contact materials (FCM) has been developed and validated. The proposed method includes migration tests, according to Commission Regulation (EU) 10/2011, using four food simulants (A, B, C, and D1), followed by vortex-assisted liquid–liquid extraction (VA-LLE) and GC-Q-Orbitrap HRMS analysis in selected ion monitoring (SIM) mode, with a resolving power of 30,000 FWHM and a mass accuracy ≤5 ppm. The method was validated, showing satisfactory linearity (R2 ≥ 0.98 from 40 to 400 …