Chromatographic lipid profiling of stress-exposed cells.

Lipidomics is an emerging field of science not only due to its integral part of cell biology and biophysics but also due to the key role of lipids in the modulation of membrane physical properties, signaling, and cell death regulation. The aim of this study was to characterize changes in N-palmitoyl ceramide concentration and in the global lipid profile in macrophages challenged by oxidized low-density lipoprotein and nutrient deprived hepatocytes. For this purpose, a quantitative targeted method based on gas chromatography-mass spectrometry for the determination of total N-palmitoyl ceramide concentrations in the cellular membranes of cells under stress was used. Ultrahigh-performance liquid chromatography-quadrupole-time of flight mass spectrometry was applied for the comprehensive profiling of lipids. In essence, we found that both models of cellular stress caused an increase in N-palmitoyl ceramide levels. In addition, increased levels of other ceramides were observed as well as up- and down-regulation of several other lipid species.

Characterization of organic compounds in aerosol particles from a coniferous forest by GC-MS.

Atmospheric aerosol particles were collected in a Finnish Scots pine forest as part of a European Union project. Sampling was done in March-April 2003 with a high-volume sampler. Dynamic ultrasonic-assisted solvent extraction and gas chromatography-mass spectrometry (GC-MS) were applied to the analysis of aerosol samples for analytes such as n-alkanes, polycyclic aromatic hydrocarbons (PAH), oxidized polycyclic aromatic hydrocarbons (oxy-PAHs), sesquiterpenes (SQT) and oxidized sesquiterpenes (oxy-SQT). The highest concentrations were found for the n-alkanes, which were present in a wide range (C11-C32) indicating both biogenic and anthropogenic sources. PAH compounds were found in every sample while oxy-PAH compounds were present in low concentrations in a few samples. A few oxidized monoterpenes, most notably (-)-verbenone and pinonaldehyde, were found in several samples in concentrations clearly exceeding the PAH concentrations. The effect of temperature could be seen in most samples, where the concentrations of n-alkanes declined with decreasing temperatures. Particle formation events were accompanied by higher concentrations of heavy n-alkanes, verbenone and pinonaldehyde.

Comparison of gas chromatography-mass spectrometry and capillary electrophoresis in analysis of phenolic compounds extracted from solid matrices with pressurized hot water.

Self-constructed pressurized hot water extraction (PHWE) equipment was used in dynamic mode to extract spiked phenolic compounds (phenol, 3-methylphenol, 4-chloro-3-methylphenol and 3,4-dichlorophenol) from sea sand and soil. Phenols were analyzed by both gas chromatography-mass spectrometry (GC-MS) and capillary zone electrophoresis (CZE) to compare the techniques and to find out if CZE is a suitable tool for analysis of phenols extracted from environmental matrix. Good recoveries of phenols spiked in sea sand were achieved at all PHWE temperatures (50, 100, 200, 300 C). GC-MS studies showed that phenols were selectively extracted from soil at 50 C but various other compounds (e.g. polyaromatic hydrocarbons) were extracted along with the phenols at 300 degrees C. In the case of CZE, phenols extracted from the soil, at 300 C were separated with good resolution at pH 9.7, and co-extracted compounds did not interfere with the analysis. The analytical values obtained by GC-MS and CZE were generally of similar magnitude.

Destruction of PAHS from soil by using pressurized hot water extraction coupled with supercritical water oxidation.

Chemical processes utilizing water both as extraction solvent and reaction medium are promising "Green Chemistry" alternatives to conventional techniques. Equipment for on-line coupled hot water extraction and supercritical water oxidation was constructed to extract polyaromatic hydrocarbons and toluene from sea sand followed by oxidation using hydrogen peroxide. The effectiveness of the technique is based on the physico-chemical properties of heated and pressurized water. Extraction efficiency increased with temperature and time; the best results were obtained at 300 degrees C with 40 min extraction time. In the oxidation stage, conversion of the PAHs increased with reaction time and oxidant concentration and the best conversion (97.0-99.9%, depending on the compound) was obtained at 425 degrees C with 43 s reaction time. Benzaldehyde and benzoic acid were the most abundant reaction intermediates in the oxidation process. In addition, phenol, p-cresol, and benzyl alcohol were found as intermediates. The intermediates originated mainly from toluene, which was present in much greater concentration than PAHs in the reaction medium.