Search results for "Gas Chromatography"

Identification of diterpenes in canvas painting varnishes by gas chromatography-mass spectrometry with combined derivatisation.

2004

A derivatisation method that combines the formation of ethyl esters from the carboxylic groups and trimethylsilyl ethers from hydroxyl groups of the components of diterpenic resins is presented in this paper. This methodology involves two experimental steps: (1) formation of ethyl esters using ethyl chloroformate; and (2) the esterified compounds are lead to react with trimethylsilylimidazole to form the corresponding trimethylsilyl ethers. The main advantage of the proposed method is the possibility of performing simultaneously the analysis of amino acids from proteins, fatty acids from drying oils, and diterpenic compounds from natural resins usually found in works of art. This methodolog…

Study of Burseraceae resins used in binding media and varnishes from artworks by gas chromatography–mass spectrometry and pyrolysis-gas chromatograph…

2005

In the present work, a study attempting to characterize the Manila elemi and Mexican copal resins from the Burseraceae family, which are used as components of varnishes and binding media of artworks, has been carried out. A new GC-MS method involving the use of methyl chloroformate as derivatisation reagent has been proposed. A second method which uses pyrolysis-GC-MS and hexamethyldisilazane as derivatization reagent has also been applied. Characterization of the main components of the mono-, sesqui- and triterpenoid fractions occurring in the raw materials has been achieved. Both alpha- and beta-amyrin have been established as the major triterpenoid compounds occurring in these resins tog…

Determination of pesticides and their degradation products in soil: critical review and comparison of methods

2004

18 páginas, 5 figuras, 5 tablas.

A simple protocol for extraction and detection of pyrazines produced by fungi in solid state fermentation

1992

A protocol for the extraction and detection of pyrazines produced by fungi in Solid State Fermentation that gave good recovery of these compounds was devised together with specific techniques for detection by Gas Chromatography (GC). The protocol involved solid-liquid and liquid-liquid extractions, concentration of the extracts and GC analysis. Extraction yields were measured from a model system in which synthetic pyrazines were added. Extracts were analysed with a gas chromatograph equipped with a thermo-ionic detector to allow specific pyrazine detection.

Comparison of Volatile Flavor Compounds Produced by Ten Strains of Penicillium camemberti Thom

1993

Abstract Volatile compounds produced by Penicillium camemberti Thom in a milk culture medium were identified using gas chromatography coupled with mass spectrometry. Volatile compounds were mainly methyl ketones and their corresponding secondary alcohols, fatty acids, and the alcohols 3-methylbutanol, 2-methylpropanol, 3-octanol, and 1-octen-3-ol. Comparison of 10 strains of P. camemberti Thom resulted in their being grouped into 6 aromatic strain groups, This grouping seems to be useful for the selection of strains for cheese making.

Multiresidue analysis of pesticides in honey by quechers and gas chromatography mass spectrometry in tandem

2011

Botanical Origin Authentication of Polish Phacelia Honey Using the Combination of Volatile Fraction Profiling by HS-SPME and Lipophilic Fraction Prof…

2019

Eleven samples of Polish Phacelia tanacetifolia Benth., three Brassica napus and one Salix spp. honeys were characterized by melissopalynology and analysis of the compositions of their volatile fractions. Headspace solid-phase microextraction coupled with gas chromatography mass spectrometry (HS-SPME/GC–MS) using PDMS/CAR/DVB fiber was used for the isolation of low-molecular weight compounds which create a volatile fraction. To differentiate and indicate the most representative unifloral samples, chemometric techniques such as principal component analysis (PCA) and hierarchical-tree clustering (HTC) were applied to the dataset of the chromatographic fingerprints. Based on the obtained resul…

Traditional and new analytical methodology

2010

International audience

Polycyclic aromatic hydrocarbons (PAHs) in coffee brew samples: analytical method by GC-MS, profile, levels and sources.

2009

Roasting is a crucial step for the production of coffee, as it enables the development of color, aroma, and flavor, which are essential for the characterization of the coffee quality. At the same time, roasting may lead to the formation of not desirable compounds, such as polycyclic aromatic hydrocarbons (PAHs). In this paper, we report a method for PAHs determination in coffee brew, based on saponification and liquid-liquid extraction with small volumes of hexane, with exclusion of further processes of purification since we analyze the extract by gas chromatography with mass spectrometric detectors in the single ion monitoring mode (SIM). The total concentration of the 28 compounds investi…

Determination of usnic and perlatolic acids and identification of olivetoric acids in Northern reindeer lichen (Cladonia stellaris) extracts

2010

AbstractThe ecologically important lichen Cladonia stellaris forms thick carpets in boreal forest floors. In addition to affecting temperature and water conditions in the soil underneath, the secondary metabolites formed by the lichen layer are of ecological interest. In this paper, we investigated the distribution of lichen acids in C. stellaris collected at different latitudes in Finland and developed methods to quantify the two optical enantiomers of usnic acid separately. The lichen extracts were analysed by high-performance liquid chromatography (HPLC) with UV and mass spectrometric (MS) detection and by gas chromatography with flame ionization (GC-FID) and MS detection. Usnic acid and…