نتایج جستجو برای: volatile organic compounds
تعداد نتایج: 425311 فیلتر نتایج به سال:
Atmospheric processing of aromatic compounds, which are known pollutants in urban air occurring predominantly from road transport sources, are a major contributor to photochemical oxidant formation as evidenced by the formation of ozone. It is believed that urban atmospheres contain a mixture of in excess of 100 speciated aromatic volatile organic compounds (VOC). Recent studies in understandin...
The emission rates of volatile organic compounds (VOCs) were measured to investigate the emission characteristics of five types of common furniture products using a 5 m(3) size chamber at 25°C and 50% humidity. The results indicated that toluene and α-pinene are the most dominant components. The emission rates of individual components decreased constantly through time, approaching the equilibri...
Proton-transfer reaction mass spectrometry (PTR-MS) is a technique developed almost exclusively for the detection of gaseous organic compounds in air. Volatile organic compounds (VOCs) in air have both natural and anthropogenic sources. Natural sources include the emission of organic gases by living objects, both plants and animals. A well-known example, which is discussed later in this review,...
OBJECTIVE To determine if non-elite athletes undertaking short duration running exercise adjacent to a busy roadway experience increased blood levels of common pollutant volatile organic compounds (benzene, toluene, ethylbenzene and xylene (BTEX)). DESIGN AND SETTING The study was observational in design. Participants (nine males/one female non-elite athletes) ran for 20 min, near a busy road...
Urban trees can produce a number of benefits, among them improved air quality. Biogenic volatile organic compounds (BVOCs) emitted by some species are ozone precursors. Modifying future tree planting to favor lower-emitting species can reduce these emissions and aid air management districts in meeting federally mandated emissions reductions for these compounds. Changes in BVOC emissions are cal...
BACKGROUND Expired gas (exhalome) analysis of ventilated critical ill patients can be used for drug monitoring and biomarker diagnostics. However, it remains unclear to what extent volatile organic compounds are present in gases from intensive care ventilators, gas cylinders, central hospital gas supplies, and ambient air. We therefore systematically evaluated background volatiles in inspired g...
Chromatography is an analytical technique employed for purification and separation of organic and inorganic substances including characterisation and quantitative measurement of compounds (table). Basically there are two types: l. Gas chromatography (GC), 2. Liquid chromatography (LC). Although discovered in 1906 by Tshett, developed in the 1950s as the GC technique where the mobile phase are g...
The development of colorimetric sensor arrays for the detection of volatile organic compounds is reported. Using an array of chemo-responsive dyes, enormous discriminatory power is created in a simple device that can imaged easily with an ordinary flat-bed scanner. High sensitivities (ppb) have been demonstrated for the detection of biologically important analytes, including amines, carboxylic ...
AIMS To determine the concentrations of pentane (a marker of lipid peroxidation) and other volatile organic compounds in the breath of patients with schizophrenia. METHODS Volatile organic compounds were assayed by gas chromatography/mass spectroscopy (GC/MS) in 88 subjects--25 with acute schizophrenic psychosis, 26 with psychiatric disorders other than schizophrenia, and 37 normal volunteers...
Volatile organic compounds (VOCs) may frequently contaminate groundwater and pose threat to human health when migrating into the unsaturated soil zone and upward to the indoor air. The kinetic of chemical oxidation has been investigated widely for dissolved VOCs in the saturated zone. But, so far there have been few studies on the use of in situ chemical oxidation (ISCO) of vapour phase contami...
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