Semivolatile compounds species

Owing to their irregular shapes the majority of the particles present in an indoor environment have large surface areas, which provide an opportunity for particles to serve as sinks for a variety of organic species. Semivolatile substances are found both in the particulate and in the vapour phases, volatile compounds occur mostly in the gas phase and substances with very low vapour pressure are adsorbed almost exclusively. In addition to the surface area of the particles, the vapour pressure of organic compounds also plays an important role in determining whether they will be found in the gas phase or adsorbed on particle matter. More information on particle chemistry is provided in Sect. 4.3. 

The experiments carried out diuing the January 2005 EUPHORE campaign consisted mostly of D-1, D4, D-5 and D-7 nms (Table 1). To determine the particle size, number and volume concentrations the Scanning Mobility Particle Analyzer (SMPS) was used and the particle mass was continuously monitored using TEOM. NOx and NOy species were monitored using chemiluminescence and Foiuier Transfer Infrared (FTIR) instruments. After several hours of exposure, the samples for semivolatile organic compound s (SVOC) analysis... 

It is well known that ultrasound has been applied to some organic substrates of environmental interest either to convert them to compounds which are less harmful than the original substrates or to extract species from particulate matter. Sonication is usually recommended for pretreatment of solid environmental samples for the extraction of nonvolatile and semivolatile organic compounds from solids such as soils, sludges and wastes since unsophisticated instrumentation may be used and separations can be performed in a short time using diluted reagents and low temperatures. 

The vial equilibration method is the most common in vitro method for determining partition coefficients for volatile or semivolatile materials and has been used most successfully for volatile organic solvents (Gargas et al., 1988). Tissues are harvested from the species of interest and incubated with the test compoxmd imtil equilibrium is reached between the tissue and the headspace in the vial. The blood/air or tissue/air partition coefficients are given by the ratio of the concentrations of the chemical in the blood or tissue relative to its concentration in the headspace. Tissue-blood partition coefficients are calculated from the respective tissue/air and blood/air values. A number of operational equations have been derived to calculate these ratios xmder specific experimental conditions. Time to steady state is critical and should be optimized for the test compoxmd. Metabolism of the compound in exposed tissue samples must be controlled. Analysis is performed by gas chromatography in a verified linear range. Human tissues can be obtained from tissue bank organizations to provide species specificity to models developed with human data. To estimate... 

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