A method for the determination of the organic acids directly in the urine employing derivatization with trimethyloxonium tetrafluoroborate as a methylating agent and sequential extraction by head space and direct immersion/solid phase microextraction is reported. Furoic acid, hippuric acid, methylhippuric acid, mandelic acid, phenylglyoxylic acid and trans, trans muconic acid contained in urine and proposed by the American Conference of Governmental Industrial Hygienists as biological exposure indices were determined after a fast and economically convenient preparation step and sensitive gas chromatography-ion trap-mass spectrometry/tandem mass spectrometry analysis. Urine is rather a complex sample and hence the acquisition method required specific GC-MS instrumentation capable of supporting the changeover, fully automated during a single chromatographic separation, from mass to tandem mass spectrometry and both chemical and electron ionization modes. The automation of the analytical method provides a number of advantages, including reduced analysis time for both routine analysis and method development, and greater reproducibility. The equilibrium and kinetics of this substances vs head space/direct immersion-solid phase microextraction were investigated and evaluated theoretically.
The concentrations of harmful products in the circuit were negligible and were lower using the new-generation absorbers. Using Amsorb Plus, the temperatures in the canisters were lower than with the other two absorbers.
Ambient Particulate Matter (PM) has been shown to be associated with cardiopulmonary diseases and lung cancer. Several groups of investigators have shown that the size of the airborne particles and their surface area determine the potential to elicit inflammatory injury and other mechanisms of adverse cellular effects. Because traffic is an important source of PM, it seems obvious that physicochemical characterization of vehicles exhaust emission has an important impact on both quantitative and qualitative aspects of ambient PM. In the present study the exhaust emissions of 8 vehicles of different categories were analyzed to attempt to differentiate them. For such purpose the particulate was collected on SPME fibers exposed to the exhaust emission for 150 s. The particulate was first characterized by micro-Raman spectroscopy and then subjected to Fast Gas Chromatography-Mass Spectrometry analyses for the chemical identification of the Polycyclic Aromatic Hydrocarbons (PAHs) compounds, the organic fraction of particulate matter in air pollution with a major role in the toxicity, notably via its effects on inflammation. Both the particle count and the PAHs compositional data were assembled to be interpreted by Principal Components Analysis. This multivariate analysis grouped the data according mainly to the naphthalene amount, as well as the volume concentration of the particles smaller than 0.5 μm, suggesting that the different exhaust emissions could be easily differentiated. With this new methodology, future research should aim at establishing a mechanism of formation during internal engine combustion processes in order to obtain a clearer picture of the inflammatory and carcinogenic mechanisms of PM in the lungs.
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