Search results for "Extraction"

Application of capillary electrophoresis-mass spectrometry for determining organic food contaminants and residues.

2008

Food contamination continues to be a serious problem around the world. Surveillance of chemical contaminants in foods is important not only for public health but also because of the negative economic impact of contamination. From the analytical perspective, analysis of contaminants in food is an extremely challenging area. There is a wide variety of questions, ranging from the quantification of extremely low levels of individual components to the detailed assessment and evaluation of the analytical technique possibilities. This review considers the applications of CE coupled to MS detection (CE-MS) for the analysis of organic contaminants in food. Analytical information on sample concentrat…

Extended Poster Abstract: Open Source Solution for Massive Map Sheet Georeferencing Tasks for Digital Archiving

2010

Scanned maps need to be georeferenced, to be useful in a GIS environment for data extraction (vectorization), web publishing or spatially-aware archiving. Widely used software solutions with georeferencing functionality are designed to suit a universal scenario for georeferencing many different kinds of data sources. Such general nature also makes them very time-consuming for georeferencing a large number of map sheets to a known grid. This work presents an alternative scenario for georeferencing large numbers of map sheets in a time-efficient manner and implements the approach as the MapSheetAutoGeoRef plug-in for the freely available open source Quantum GIS [1].

Feature selection: A multi-objective stochastic optimization approach

2020

The feature subset task can be cast as a multiobjective discrete optimization problem. In this work, we study the search algorithm component of a feature subset selection method. We propose an algorithm based on the threshold accepting method, extended to the multi-objective framework by an appropriate definition of the acceptance rule. The method is used in the task of identifying relevant subsets of features in a Web bot recognition problem, where automated software agents on the Web are identified by analyzing the stream of HTTP requests to a Web server.

Sensory and chemical drivers of wine minerality aroma: An application to Chablis wines

2017

The goal of this work was to evaluate the effect of vineyard position on the minerality of wines and to establish relationships between minerality scores, sensory descriptors and chemical composition. Sensory analyses included minerality rating and free description performed by wine professionals under two conditions: orthonasal olfaction alone and global tasting. Chemical characterization included analysis of major and minor volatile compounds, volatile sulphur compounds, mercaptans, metals, anions and cations. Results showed a significant effect of the river bank on wine minerality scores only in the orthonasal olfaction condition, samples from the left being more mineral than those from …

Inverse-voltammetric determination of bismuth in biomaterials with computer assisted peak evaluation. part 3. Bismuth determination in wine, grapes a…

1989

The ultra trace element bismuth is regulary found in wine on an average of about 0.1 ppb. Very low bismuth contents were also determined in soil and different biomaterials. In spite of those very low quantities even speciation experiments show results, so far that about 90% of the bismuth in the grapes is water-soluble, resumably as saccharic acids. For detecting such low quantities a very sensitive method of differential pulse anodic stripping voltammetry was developped. The speciation experiments were carried out by fractional extraction.

Quantitative determination of sotolon in wines by high-performance liquid chromatography

1993

Sotolon (4,5-dimethyl-3-hydroxy-2(5H)-furanone) is a key flavour compound in the french flor-sherry “Vin jaune”. This compound was determined quantitatively by extraction of 25 ml of wine on a XAD-4 resin, elution with diethyl ether, separation by HPLC on a Lichrospher 100 Diol column, elution with dichloromethane/hexane (60/40) and UV detection at 232 nm. The amount of sotolon in “Vin jaune” (120 to 268 μg/l) was related to the development of the yeast film over a period of 6 years. Only 6 to 51 μg/l were found in the “Vin de paille” which is made with overmaturated grapes of the same Savagnin vine-plant but without development of yeasts, and 80 to 140 μg/l in “Tokai” which are partly grow…

High Performance Liquid Chromatography Analysis of Grape and Wine Polyphenols

2008

Representative champagne wine extracts for gas chromatography olfactometry analysis

1997

Gas chromatography olfactometry (GCO) analysis has proved to be a powerful method to determine key compounds of food aroma, but up to now few papers involving this technique in wine aroma studies were published. An accurate representation of the olfactory quality of the extracts is necessary to ensure the reliability of the conclusions resulting from such analyses. Three commercial champagne wines were used for this study. The champagne wine extracts were obtained from three different extraction methods:  adsorption on XAD resins, solvation in dichloromethane, and extraction by demixing ethanol. Thus the extracts were tested by a panel trained on champagne wines, using a profile descriptive…

Molecularly imprinted polymer solid phase extraction of fungicides from wine samples

2014

In order to preconcentrate iprodione fungicide in white wine samples, molecularly imprinted polymers (MIPs) specific for iprodione were synthesized using two polymerization approaches: precipitation (MIPp) and bulk polymerization (MIPb). A comparison of the performance of the MIPs and the corresponding non-imprinted polymers (NIPs) was conducted in batch studies. In this case, the MIPp revealed better recognition properties toward iprodione in wine samples than the MIPb. The MIPp and MIPb were then used as sorbents on solid phase extraction cartridges (MISPEp and MISPEb consecutively) in order to pre-concentrate iprodione from white wine samples. The optimization of the MISPE elution step w…

Comparison of different sample treatments for the analysis of ochratoxin A in must, wine and beer by liquid chromatography.

2004

Abstract Ochratoxin A (OTA) is a mycotoxin produced by some species of Aspergillus and Penicillium verrucosum. It has been found in foods and feed all over the world. There is a great concern about OTA because it is nephrotoxic and probably, carcinogenic to humans. Most of analytical methods developed for OTA in wine, beer and other products are based on LC with fluorescence detection (LC–FLD). In the present work, various procedures for extraction and/or clean-up for determination of OTA in musts, wine and beer by LC–FLD were compared: (1) dilution with polyethylen glycol 8000 and NaHCO3 solution and clean-up an on immunoaffinity column (IAC); (2) extraction with chloroform and IAC clean-u…