Search results for "Gas Chromatography"

PCDTs in the environment

1997

Abstract Polychlorinated dibenzothiophenes (PCDTs) are sulfur analogues of polychlorinated dibenzofurans. Recently, PCDTs have been found in stack gas and fly ash samples, pulp mill effluents, sediments and in some aquatic organisms. PCDTs have been analyzed by high resolution GC/MS and by other GC-MS techniques. Combustion is until now the major known source of PCDTs in the environment. Tri-, tetra- and pentaCDTs in concentrations approaching those of PCDTs have been analyzed in some samples from waste incineration and metal reclamation. Concentrations of PCDTs in pulp mill effluents have been found to be quite low. 2378-TeCDT was found to be the major TeCDT isomer in some pulp mill efflue…

Chlorocymenes, cymenenes and other chlorohydrocarbons in pulp mill effluents, sludges and exposed biota

1992

Abstract Polychlorinated cymenes (PCYMS) and cymenenes (PCYMD) were analyzed by GC/LRMS/SIM in effluents and sludges of three different pulp mills and in fish and mussels exposed to pulp mill effluents. The levels of PCYMS+PCYMD were 0.3–4.8 μg/l in total effluents,

Absorption of polycyclic aromatic hydrocarbons by pinus bark: analytical method and use for environmental pollution monitoring in the Palermo area (S…

2007

Abstract In the light of using biomaterial as pollutants sorbents for the environmental biomonitoring, we report here the results of the absorption of polycyclic aromatic hydrocarbons (PAHs) by pine bark. Quantitative analysis of 19 different polycyclic aromatic compounds was performed, after Soxhlet extraction in dichloromethane, by means GC–MS technique. Pinus was chosen due to its wide distribution in the Mediterranean area. The passive absorption of PAH by pine bark in the metropolitan areas allowed us to evaluate the air quality of Palermo. The obtained results showed a very high range of PAHs concentrations, from 33 μg/kg (bark dry weight), as ΣPAHs, at the control site to 1015 μg/kg …

Gas chromatography-mass spectrometry study of polycyclic aromatic hydrocarbons in grass and milk from urban and rural farms

2000

Polycyclic aromatic hydrocarbon (PAH) levels were studied in grass and milk sampled at two farms, one located in a non-contaminated, rural area, and another located in a urban area close to PAH sources such as highways, busy roads, fuel-powered trains and a steel plant. PAH concentration were measured by gas chromatography coupled to mass spectrometry (GC-MS) using internal deuterated standards. In grasses, unexpectedly, although the sum of PAH concentrations was only slightly higher at the urban farm (83.1 ± 16.1 ng g−1) than the rural farm (51.8 ± 10.6 ng g−1), this difference was not observed for all PAH members. This absence of a striking difference of PAH levels between urban and rura…

Presence of phosphorylatedO-ribosyl-adenosine In T-ψ-stem of yeast methlonine initiator tRNA

1989

We report in this paper on isolation and characterization of two unknown nucleosides G* and [A*] located in the T-psi-stem of yeast methionine initiator tRNA, using the combined means of HPLC protocols, real time UV-absorption spectrum, and post-run mass spectrometry by electron impact or fast atom bombardment. The G* nucleoside in position 65 was identified as unmodified guanosine. The structure of the unknown [A*] in position 64 was characterized as an isomeric form of O-ribosyl-adenosine by comparison of its chromatographic, UV-spectral and mass spectrometric properties with those of authentic O-alpha-ribofuranosyl-(1"----2')-adenosine isolated from biosynthetic poly(adenosine diphosphat…

1984

Analyse von Copolymeren aus Vinylestern und Acrylestern

1978

Die Copolymeren aus Vinyl- und Acrylestern werden in abgeschmolzenen Ampullen durch 2 M NaOH verseift. Die aus den Vinylester-Grundbausteinen gebildeten Sauren werden durch potentiometrische Titration bestimmt; liegen verschiedene Vinylester nebeneinander vor, so wird das Mengenverhaltnis der Sauren gaschromatographisch ermittelt. Die bei der Verseifung aus den Acrylester-Grundbausteinen entstehenden Alkohole werden gaschromatographisch identifiziert und gegen tert-Butanol als internen Standard quantitativ bestimmt. Ein besonderer Vorteil der Methode besteht darin, das auch wasrige Dispersionen ohne vorherige Abtrennung des Copolymeren eingesetzt werden konnen. The copolymers from vinyl est…

Biomolecular characterization of wild sicilian oregano: phytochemical screening of essential oils and extracts, and evaluation of their antioxidant a…

2013

An extensive survey of wild Sicilian oregano was made. A total of 57 samples were collected from various sites, followed by taxonomic characterization from an agronomic perspective. Based on morphological and production characteristics obtained from the 57 samples, cluster analysis was used to divide the samples into homogeneous groups, to identify the best biotypes. All samples were analyzed for their phytochemical content, applying a cascade-extraction protocol and hydrodistillation, to obtain the non volatile components and the essential oils, respectively. The extracts contained thirteen polyphenol derivatives, i.e., four flavanones, seven flavones, and two organic acids. Their qualitat…

Applications of Electromigration Techniques: Applications of Electromigration Techniques in Food Analysis

2013

Electromigration techniques, including capillary electrophoresis (CE), are widely used for separation and identification of compounds present in food products. These techniques may also be considered as alternate and complementary with respect to commonly used analytical techniques, such as high-performance liquid chromatography (HPLC), or gas chromatography (GC). Applications of CE concern the determination of high-molecular compounds, like polyphenols, including flavonoids, pigments, vitamins, food additives (preservatives, antioxidants, sweeteners, artificial pigments) are presented. Also, the method developed for the determination of proteins and peptides composed of amino acids, which …

Fruit physical, chemical and aromatic attributes of early, intermediate and late apricot cultivars.

2010

BACKGROUND: In order to reach good fruit quality, apricots require a balance of sugars and acids as well as a strong apricot aroma. In this study, fruit quality of early, intermediate and late apricot cultivars was evaluated by measuring physical, chemical and olfactory attributes. Multivariate analysis of quality and aroma attributes was used to identify groups of similar cultivars and association with ripening season. RESULTS: Physical, chemical and aromatic attributes showed great variation amongcultivars but no relation to ripening season. Aromatic profiles (34 volatiles) of fruit tissues indicated qualitative and quantitative differences among cultivars. Ninfa and Mandorlon were riches…