Search results for "gas chromatography."

Chlorinated and methylated dibenzothiophenes: Preparation of the model compounds and their analysis from some environmental samples

1990

Abstract Polychlorinated and polymethylated dibenzothiophenes if occuring in the environment can cause environmental hazards and problems like chlorinated dibenzodioxins and dibenzofurans. Some chlorinated and methylated dibenzothiophenes have been synthesized to serve as model compounds in environmental and toxicological analysis. The synthesis mixtures and some environmental samples have been analyzed by high resolution GC/low resolution MS. This investigation showed that the concentrations of these compounds in environmental samples were below ppb level but it did not exclude the occurence of these compounds in our environment. More investigation is needed.

Phytoscreening as an efficient tool to delineate chlorinated solvent sources at a chlor-alkali facility

2017

Chlorinated ethenes (CE) are among the most common volatile organic compounds (VOC) that contaminate groundwater, currently representing a major source of pollution worldwide. Phytoscreening has been developed and employed through different applications at numerous sites, where it was generally useful for detection of subsurface chlorinated solvents. We aimed at delineating subsurface CE contamination at a chlor-alkali facility using tree core data that we compared with soil data. For this investigation a total of 170 trees from experimental zones was sampled and analyzed for perchloroethene (PCE) and trichloroethene (TCE) concentrations, measured by solid phase microextraction gas chromato…

POPs and organic polysufides in sediments of Lake Ladoga

2007

Abstract The study included one station close to a pollution source (depth 59 m) and another far from polluted areas (depth 40 m). Samples were analysed for organic chlorine, bromine and sulfur compounds. Samples taken with a corer were sliced to the layers of 0–1, 1–4, 4–7 cm etc. down to the depth of 34 cm. The dating was made with two independent methods, the 210Po method and with the soot particle counting method. The analyses were made with a multiresidue method. Gas chromatography was connected to low resolution mass spectrometry (LRMS) or to high resolution mass spectrometry (HRMS). A different extraction was applied to screen the possible occurrence of polysulfides. Typical chloroph…

Strategies for the rapid characterization of metals and organic pollutants in solid wastes and contaminated soils by using mass spectrometry

1998

Abstract Hyphenated techniques involving mass spectrometry (MS) such as ICP-MS, GC–MS and LC–MS are the most powerful tools for both qualitative and quantitative characterization of metals and organic pollutants in previously dissolved or extracted samples. However a considerable analytical effort is required in developing simple and general sample preparation strategies for the complete characterization of toxic substances in solid wastes and soils. This article gives a critical review of the state-of-the-art and future perspectives for rapid procedures to evaluate the pollution of soils and sediments, also considering new alternatives like flow injection analysis–MS and direct sampling MS.

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