Gas Chromatography Coupled To A Mass Spectrometer Research Articles

English

The Casearia species (Salicaceae) occur in the tropics and subtropics and their extracts are rich in clerodane-type diterpenes, known as casearins. According to the literature, extracts from Casearia sylvestris exhibit cytotoxic and genotoxic effects in different tumor cell lines, possibly related to the casearins. On the other hand, there are few studies related to the DNA damages of the essential oils from this species. This study is aimed at evaluating DNA damages promoted by the essential oil from leaves of C. sylvestris collected in Rio de Janeiro. The essential oil was obtained from fresh leaves (1.5 kg) by hydrodistillation for 2 h in a Clevenger-type apparatus, and analyzed both by gas chromatography coupled to a mass spectrometer (GC-MS) and gas chromatography coupled to a flame ionization detector (GC-FID). These analyses revealed a very diversified (n = 21 compounds) volatile fraction composed mainly of non-oxygenated sesquiterpenes (72.1%), and the major component was identified as α-humulene (17.8%). Genotoxicity was evaluated by the comet assay, showing DNA damages, mainly of classes 3 and 4 at 4.0 µg/ml (p < 0.05) according to the damage index (DI). This is the first demonstration of DNA damages in response to the essential oil of C. sylvestris. Key words: A549, α-humulene, comet assay, sesquiterpenes.

Assessment of Ethyl Carbamate Contamination in Cachaça (Brazilian Sugar Cane Spirit)

Cachaça is a sugar cane spirit produced in Brazil. Ethyl carbamate (EC), a potential carcinogenic compound, may be present in cachaça above the limit established by law. The purpose of this study was to determine the concentration of ethyl carbamate in cachaças recently produced in Brazil in order to verify their compliance with the law. The concentration of ethyl carbamate was determined in 376 samples of cachaça through gas chromatography coupled to a mass spectrometer (GC-MS). The mean value of ethyl carbamate in the cachaças analyzed was 145 µg/L, and 24% of them were not in compliancy with the law (EC < 210 µg/L). However, compared to previous studies, advances have been observed regarding the adjustment of cachaças to the legal limit. Cachaças produced in large distilleries through continuous column distillation presented a mean value of 200 µg/L of ethyl carbamate. Cachaças produced in small distilleries using pot still distillation presented a mean content of 74 µg/L. Small producers have been more engaged in using good manufacturing practices to guarantee the quality of cachaças.

Different population densities and continuous feeding by Oligonychus yothersi (McGregor) (Acari: Tetranychidae) affect the emissions of herbivore-induced plant volatiles on avocado (Persea americana Mill. cv. Hass) shoots under semi-field conditions

ABSTRACTPlants attacked by insects and mites release blends of herbivore-induced plant volatiles (HIPVs), which act as chemical cues that attract predators and/or repel herbivores alongside alerting neighbouring plants. The chemical profiles of avocado (Persea americana Mill. Cultivar Hass) shoots infested with the foliar mite Oligonychus yothersi (Acari: Tetranychidae) were analysed using a gas chromatograph coupled to a mass spectrometer (GC-MS); the different collections of volatiles were performed under semi-field conditions in summer. Four infestation treatments were applied to the avocado shoots (uninfested plant or control; low, medium and high mite-infestation levels). The chemical profiles collected in situ changed qualitatively and quantitatively after infestation, increasing the emissions of (Z)-β-ocimene, (E)-β-ocimene, β-linalool, α-farnesene, farnesyl cyanide and methyl salicylate (MeSA) as opposed to those of the uninfested shoots. The amount of HIPVs emitted by the avocado shoots with the highest O. yothersi population density (250 ± 10 mites per leaf) were greater than those of the shoots infested with the lower population density (60 ± 10 mites per leaf); to the emissions of (E)-β-ocimene, sesquiterpenes and MeSA at higher amounts even after seventeen days of continuous infestation. Likewise, the emissions of HIPVs increased with each infestation level; also fluctuating between collecting dates, which indicates that environmental conditions maximized or constrained those emissions. In addition, the damaged foliar area increased with higher O. yothersi population densities after seventeen days of infestation. These results indicate that higher mite-population densities and continuous O. yothersi-feeding increases the amounts of HIPVs emitted by O. yothersi-infested shoots in summer.

PM10 emissions and PAHs: The importance of biomass type and combustion conditions

ABSTRACTThe aim of the present work was to investigate the impact of biomass combustion with respect to conditions and fuel types on particle emissions (PM10) and their PAHs content. Special concern was on sampling, quantification and characterization of PM using different appliances, fuels and operating procedures. For this purpose different lab-scale burning conditions, two pellets stoves (8.5 and 10 kW) and one open fireplace were tested by using eight fuel types of biomass. An analytical method is described for the quantitative determination of 16 PAHs using liquid-liquid extraction and subsequent measurement by gas chromatography coupled to a mass spectrometer (GC-MS). Average PM10 emissions ranged from about 65 to 170 mg/m3 at lab-scale combustions with flow oxygen at 13% in the exhaust gas, 85–220 mg/m3 at 20% O2, 47–83 mg/m3 at pellet stove of 10 kW, 34–69 mg/m3 at pellet stove of 8.5 kW and 106–194 mg/m3 at the open fireplace. The maximum permitted particle emission limit is 150 mg/m3. Pellets originated from olive trees and from nonmixture trees were found to emit the lowest particulate matter in relation to the others, so they are considered healthiest and suitable for domestic heating reasons. In general, the results show that biomass open burning is an important PM10 and PAHs emission source.

Effect of seasonal population fluctuation in the temporal and spatial distribution of polycyclic aromatic hydrocarbons in a subtropical estuary

Abstract Guaratuba Bay is a subtropical estuary located in an Environmental Protection Area and between two touristic cities, which are strongly influenced by seasonal increased population during austral summer. To evaluate the recent introduction of polycyclic aromatic hydrocarbons (PAHs) in Guaratuba Bay, samples of surficial suspended particulate matter (SPM) were collected at 22 sites and at three different times. PAHs were determined by gas chromatography coupled to a mass spectrometer (GC/MS). The studied area was sectored according to hydrological parameters. The highest PAH concentrations were observed during the Carnival period due to the tourism and population increase. Spatially, the highest concentrations were verified in the mesohaline and euhaline estuarine regions and were related to the environmental characteristics that facilitate material accumulation and the proximity to ship docks, respectively. The diagnostic ratios and the principal component analysis suggest that the main sources of PAHs are petrogenic inputs related to the boat traffic.

Discovery of an oviposition attractant for gravid malaria vectors of the Anopheles gambiae species complex.

BackgroundNew strategies are needed to manage malaria vector populations that resist insecticides and bite outdoors. This study describes a breakthrough in developing ‘attract and kill’ strategies targeting gravid females by identifying and evaluating an oviposition attractant for Anopheles gambiae s.l.MethodsPreviously, the authors found that gravid An. gambiae s.s. females were two times more likely to lay eggs in lake water infused for six days with soil from a natural oviposition site in western Kenya compared to lake water alone or to the same but autoclaved infusion. Here, the volatile chemicals released from these substrates were analysed with a gas-chromatograph coupled to a mass-spectrometer (GC-MS). Furthermore, the behavioural responses of gravid females to one of the compounds identified were evaluated in dual choice egg-count bioassays, in dual-choice semi-field experiments with odour-baited traps and in field bioassays.ResultsOne of the soil infusion volatiles was readily identified as the sesquiterpene alcohol cedrol. Its widespread presence in natural aquatic habitats in the study area was confirmed by analysing the chemical headspace of 116 water samples collected from different aquatic sites in the field and was therefore selected for evaluation in oviposition bioassays. Twice as many gravid females were attracted to cedrol-treated water than to water alone in two choice cage bioassays (odds ratio (OR) 1.84; 95% confidence interval (CI) 1.16-2.91) and in experiments conducted in large-screened cages with free-flying mosquitoes (OR 1.92; 95% CI 1.63-2.27). When tested in the field, wild malaria vector females were three times more likely to be collected in the traps baited with cedrol than in the traps containing water alone (OR 3.3; 95% CI 1.4-7.9).ConclusionCedrol is the first compound confirmed as an oviposition attractant for gravid An. gambiae s.l. This finding paves the way for developing new ‘attract and kill strategies’ for malaria vector control.Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-015-0636-0) contains supplementary material, which is available to authorized users.

A Study on the Decomposition of Lithium-Ion Battery Electrolytes from Different Field-Tested Hybrid Vehicles

In times of the climate change due to global warming partly caused by consumption of fossil fuels, mankind should focus on the prevention or at least reduction of exhaust gases. Emissions of cars powered by internal combustion engines (ICEs) are one source for greenhouse gases. These emissions could be decreased by electric vehicles (EVs) which are charged with regenerative energy. To evade disadvantages of EVs like range or charge time hybrid vehicles (HVs) could be an interim solution.Lithium-ion batteries (LIBs) are the energy storage system of choice for HVs due to high energy density and high reversibility.[1] However, also LIBs are limited in lifetime because of internal decomposition reactions of the electrolyte and other battery parts, but mechanisms are yet not fully understood. Another challenge in this context is the development, application and combination of suitable analytical methods due to the complex composition of a LIB electrolyte. In recent years, several investigation methods have been applied regarding electrolyte characterization and decomposition.[2-8]However, to the author´s best knowledge all investigations were realized on the laboratory scale. Herein, we report the analysis of electrolyte decomposition of battery cells from field-tested HVs.Besides the inquisitiveness about internal decomposition reactions we are also interested in safety aspects of HVs. We wanted to know how the electrolyte behaves when it escapes due to an accident. Thus, cells were opened in a laboratory hood under exposure of air. The electrolyte was collected through a small drilled hole. The solution was analyzed with gas chromatography coupled to a mass spectrometer (GC-MS) to identify organic carbonates, additives and volatile decomposition products. Quantification was done with a flame ionization detector (GC-FID). Ion chromatography (IC) was applied to gain information about the used conducting salt and its amount. Each cell contained LiPF6. Further IC experiments were carried out by hyphenation to an electrospray ionization mass spectrometer (IC-ESI-MS). Besides hydrofluoric and phosphoric acid, several fluorinated phosphates and organo phosphates could be identified. This advanced hydrolysis is partly caused by the reaction with humidity during the cell opening process.LiBF4 could be detected with IC via retention time and verified with IC-ESI-MS. It was further proven with hyphenation of IC to an inductive coupled plasma - mass spectrometer (IC-ICP-MS), inductive coupled plasma - optical emission spectroscopy (ICP-OES) and nuclear magnetic resonance (11B-NMR).This work is a demonstration of the logical combination of different (hyphenated) investigation methods for the characterization of unknown LIB electrolytes from large scale cells which were applied in field-tested HVs.We kindly thank the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety for funding of the project LithoRec II (project grant number: 16EM1025) and also the project partners for support and cooperation. Verena Naber and Constantin Lürenbaum are acknowledged for their help during sample preparation and investigations with IC and GC.[1] M. Winter, J. O. Besenhard, Chem. unserer Zeit 1999, 33, 320-332.[2] U. Heider, R. Oesten, M. Jungnitz, J. Power Sources 1999, 81-82, 119-122.[3] C. L. Campion, W. Li, B. L. Lucht, J. Electrochem. Soc. 2005, 152, A2327-A2334.[4] L. Terborg, S. Weber, F. Blaske, S. Passerini, M. Winter, U. Karst, S. Nowak, J. Power Sources 2013, 242, 832-837.[5] G. Gachot, P. RibieÌre, D. Mathiron, S. Grugeon, M. Armand, J.-B. Leriche, S. Pilard, S. Laruelle, Anal. Chem. 2010, 83, 478-485.[6] L. Terborg, S. Nowak, S. Passerini, M. Winter, U. Karst, P. R. Haddad, P. N. Nesterenko, Anal. Chim. Acta 2012, 714, 121-126.[7] B. Vortmann, S. Nowak, C. Engelhard, Anal. Chem. 2013, 85, 3433-3438.[8] L. Terborg, S. Weber, S. Passerini, M. Winter, U. Karst, S. Nowak, J. Power Sources 2014, 245, 836-840.*to whom correspondence should be addressed:sascha.nowak@uni-muenster.de

Polycyclic aromatic hydrocarbons study in atmospheric fine and coarse particles using diagnostic ratios and receptor model in urban/industrial region

Atmospheric fine and coarse particles were collected in Teflon filters in three cities of the region of the Lower Sinos River Basin of Rio Grande do Sul in the year 2010. The filters were Soxhlet extracted, and 14 priority PAHs were analyzed using a gas chromatograph coupled to a mass spectrometer (GC/MS). The principal emission sources of these compounds were assessed by using diagnostic ratios and receptor model: positive matrix factorization (PMF 3.0) of the US Environmental Protection Agency. The results of PAHs concentration for the studied year showed significant levels of high molecular weight (HMW) PAH, Ind, and BghiP, in PM2.5 in the winter season, showing the influence of mobile sources. The application of receptor model PMF 3.0 revealed that the main sources of PAHs were vehicle fleet (both diesel and gasoline), followed by coal combustion, wood combustion, and resuspension of dust. The results of the receptor modeling are in agreement with the data obtained by the ratio diagnostic.

Analysis of Gasoline Used by Motorbike-Taxi Drivers in Cotonou

In 2009, samples from itinerant stations were taken in Cotonou. Official reference gasoline stations (French and boundary African country) were also studied. The analysis was done by gas chromatography coupled to a mass spectrometer (GC-MS). The results showed appreciate difference between itinerant and official gasoline samples: ETBE (Ethyl Tert-Butyl Ether) was found in the composition of the French reference but not in the African gasolines composition. Benzene was detected at yields less than 1% in the French reference gasoline whereas in the gasoline made in the African countries benzene yields were between 2.36 and 4.39%. The ratio of toluene/benzene varied between 1.27 and 10.25 in studied gasoline and was much lower in ambient air. For major components (aromatics and paraffin compounds), we observed another heterogeneity for itinerant gasoline (probably due to numerous hands making and transport).

The PROCESS Experiment: Exposure of Amino Acids in the EXPOSE-E Experiment on the International Space Station and in Laboratory Simulations

To understand the chemical behavior of organic molecules in the space environment, amino acids and a dipeptide in pure form and embedded in meteorite powder were exposed in the PROCESS experiment in the EXPOSE-E facility mounted on the European Technology Exposure Facility (EuTEF) platform on board the International Space Station (ISS). After exposure to space conditions for 18 months, the samples were returned to Earth and analyzed in the laboratory for reactions caused by solar UV and cosmic radiation. Chemical degradation and possible racemization and oligomerization, the main reactions caused by photochemistry in the vacuum ultraviolet domain (VUV, wavelength range 100-200 nm for photon energy from 6.2 to 12.4 eV) were examined in particular. The molecules were extracted and derivatized by silylation and analyzed by gas chromatograph coupled to a mass spectrometer (GC-MS) to quantify the rate of the degradation of the compounds. Laboratory exposure in several wavelength ranges from UV to VUV was carried out in parallel in the Cologne Deutsches Zentrum für Luft- und Raumfahrt (DLR) Center and Centre de biophysique moléculaire (CBM) laboratories. The results show that resistance to irradiation is a function of the chemical nature of the exposed molecules and the wavelengths of the UV light. The most altered compounds were the dipeptide, aspartic acid, and aminobutyric acid. The most resistant were alanine, valine, glycine, and aminoisobutyric acid. Our results also demonstrate the protective effect of meteorite powder, which reemphasizes the importance of exogenic contribution to the inventory of prebiotic organics on early Earth.

Chemical Composition and Antibacterial Activity of the Essential Oil of Moroccan Juniperus phoenicea

The antibacterial activity of the essential oil from leaves of Juniperus phoenicea (Cupressaceae) and its chemical constituents were investigated in this study. The essential oil was obtained by hydro-distillation and analyzed by gas chromatography equipped with a flame ionisation detector (GC-FID), and gas chromatography coupled to a mass spectrometer (GC-MS). Sixty-three volatile compounds were identified representing 52 to 92% of the total oil compositions. The main monoterpenes were a-pinene (26.7-78.7%) and 6-3carene (7.6-15.4%). The antibacterial activity of J. phoenicea essential oil, when tested against both Gram-positive and Gram-negative bacteria, showed high activity against all bacteria tested, except Pseudomonas.

High-Precision GC-MS Analysis of Atmospheric Polycyclic Aromatic Hydrocarbons (PAHs) and Isomer Ratios from Biomass Burning Emissions

This manuscript describes an analytical method for the quantitative determination of 16-polycyclic aromatic hydrocarbons (PAHs) using accelerated solvent extraction (ASE), followed by purification on a silica cartridge, and subsequent measurement by gas chromatograph coupled to a mass spectrometer (GC-MS). The solvent extraction parameters (T = 100 oC, P = 1500 psi, t = 30 min, V = 30 ml) are optimized with dichloromethane (DCM) in order to avoid fractionation effect, thereby achieving quantitative mass recovery of PAHs. The purification of PAHs on silica cartridge eliminates the matrix effect, facilitates their enrichment from extracted solution and quantitative deter-mination in presence of an internal-standard (Pyrene-D10). The analytical protocol has been successfully used for the quantification of 16-PAHs and their isomer ratios in atmospheric aerosols collected from northern India dominated by agricultural- waste (post-harvest paddy and wheat residue) burning emissions. Based on the analysis of ambient aerosols, collected from different sites, the overall recovery efficiency for 2- to 3-ring PAHs is 85% and near 100% recovery for 4- to 6-ring compounds.

Determination of gamma-hydroxybutyric acid in dried blood spots using a simple GC-MS method with direct “on spot” derivatization

The objective of this study was the development of an accurate and sensitive method for the determination of gamma-hydroxybutyric acid (GHB) in dried whole blood samples using a GC-MS method. The complete procedure was optimized, with special attention on the sample pretreatment, and validated. Therefore, dried blood spots of only 50 μl were prepared and, after the addition of internal standard GHB-d6, directly derivatized using 100 μl of a freshly prepared mixture of trifluoroacetic acid anhydride and heptafluorobutanol (2:1). The derivatized extract was injected into a gas chromatograph coupled to a mass spectrometer (GC-MS), operating in the electron impact mode, with a total run time of 12.3 min. Method validation included the evaluation of linearity, precision, accuracy, sensitivity, selectivity, and stability. A weighting factor of 1/x(2) was chosen and acceptable intra-batch precision, inter-batch precision, and accuracy were seen. The linear calibration curve ranged from 2 to 100 μg/ml, with a limit of detection of 1 μg/ml. Our procedure, utilizing the novel approach of direct "on spot" derivatization followed by analysis with GC-MS, proved to be reliable, fast, and applicable in routine toxicology.

Determination of PAHs in diesel particulate matter using thermal extraction and solid phase micro-extraction

Determination of polycyclic aromatic hydrocarbons (PAHs) from chemical analysis of the diesel particulate matter (DPM) requires considerable sampling expertise and is often time-consuming because sample preparation demands strict extraction procedures due to the complex nature of the DPM matrix. In this study, a method to measure the emissions of the 16-U.S. Environmental Protection Agency (EPA) priority PAHs adsorbed in diesel particles has been developed. This method involves the capture of the DPM in glass microfibre filters, thermal extraction of the compounds from the particulate matrix in a thermogravimetric analyzer (TGA), determination of the concentration by means of a solid phase micro-extraction (SPME) fibre and subsequent analysis using a gas chromatograph coupled to a mass spectrometer (GC/MS). Analyses of a fully characterised DPM prepared by the National Institute of Standards and Technology, NIST (SRM 1650b), were performed and calculated errors showed that the method is capable of giving reliable quantitative data. Additionally, DPM collected from a diesel engine was analyzed and the results showed the high method sensitivity to the engine operating conditions.

CYP725A4 from Yew Catalyzes Complex Structural Rearrangement of Taxa-4(5),11(12)-diene into the Cyclic Ether 5(12)-Oxa-3(11)-cyclotaxane

Taxa-4(5),11(12)-diene is the first committed precursor of functionalized taxanes such as paclitaxel, a successful anticancer drug. Biosynthesis of taxanes in yew involves several oxidations, a number of which have been shown to be catalyzed by cytochrome P-450 oxygenases. Hydroxylation of the C-5alpha of taxa-4(5),11(12)-diene is believed to be the first of these oxidations, and a gene encoding a taxa-4(5),11(12)-diene 5alpha-hydroxylase (CYP725A4) was recently described (Jennewein, S., Long, R. M., Williams, R. M., and Croteau, R. (2004) Chem. Biol. 11, 379-387). In an attempt to produce the early components of the paclitaxel pathway by a metabolic engineering approach, cDNAs encoding taxa-4(5),11(12)-diene synthase and CYP725A4 were introduced in Nicotiana sylvestris for specific expression in trichome cells. Their co-expression did not lead to the production of the expected 5alpha-hydroxytaxa-4(20),11(12)-diene. Instead, taxa-4(5),11(12)-diene was quantitatively converted to a novel taxane that was purified and characterized. Its structure was determined by NMR analysis and found to be that of 5(12)-oxa-3(11)-cyclotaxane (OCT) in which the eight-carbon B-ring from taxa-4(5),11(12)-diene is divided into two fused five-carbon rings. In addition, OCT contains an ether bridge linking C-5 and C-12 from opposite sides of the molecule. OCT was also the sole major product obtained after incubation of taxa-4(5),11(12)-diene with NADPH and microsomes prepared from recombinant yeast expressing CYP725A4. The rearrangement of the taxa-4(5),11(12)-diene ring system is thus mediated by CYP725A4 only and does not rely on additional enzymes or factors present in the plant. The complex structure of OCT led us to propose a reaction mechanism involving a sequence of events so far unknown in P-450 catalysis.

Study of the chemical elements and polycyclic aromatic hydrocarbons in atmospheric particles of PM 10 and PM 2.5 in the urban and rural areas of South Brazil

The purpose of this work is to study the chemical elements and PAHs associated with atmospheric particulate in samples of PM 10 collected in the Metropolitan Area of Porto Alegre—MAPA, Rio Grande do Sul, Brazil. In addition, to study the chemical elements associated with particles of different fractions of PM 10–2.5 and PM 2.5 using dichotomous sampling, in urban (MAPA) and rural areas. Two types of samplers were used: HV PM 10 and Dichotomous (PM 10–2.5 and PM 2.5). Samples were collected during 2002 and 2005. The concentration of the elements Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, and Zn was determined by PIXE (Particle-Induced X-ray Emission), while the concentrations of 16 major PAHs were determined according to EPA with a gas chromatograph coupled to a mass spectrometer (GS/MS). Results showed that elements of anthropogenic origin (V, Zn, Cr, Ni, Cu, and S) were mainly associated with the fraction PM 2.5, while the soil dust (Si, Al, Ti and Fe) were found mainly on fraction PM 10–2.5. In samples of PM 10, the most frequent PAHs found were Bgp, Flt, BaA, Chr, B(b + k)F, BaP and Dba. The types of emission and their association with the atmospheric parameters were studied applying the statistical analysis of the principal component method. The main sources found in the area under study were vehicles, industries (steel mills and a coal-fired power station), dust, sea breeze, and burning.

Polycyclic Aromatic Hydrocarbons and their Molecular Diagnostic Ratios in Airborne Particles (PM10) Collected in Rio de Janeiro, Brazil

Atmospheric polycyclic aromatic hydrocarbons (PAHs) were determined in particulate matter (PM10) collected in a suburban area with industrial and vehicular emissions in the Metropolitan Area of Rio de Janeiro City (Brazil). A total of 22 samples were collected between March and August 2005 by means of a high volume PM10 sampler. The particulate matter contained in the filters was extracted ultrasonically with dichloromethane. The extracts were later analyzed by gas chromatography coupled to a mass spectrometer (GC/MS). The individual concentrations of PAHs ranged between the detection limit and 0.386 ng m−3. The PAHs concentrations observed in this study were towards the lowest end of the range of values reported for other European locations and also lower than values obtained for South America. PAHs concentrations and molecular ratios showed that light cars seem to be the main contributors to PM10 emissions, but diesel vehicles are clearly minor emission sources and industrial contributions should not be disregarded until more data are obtained.

Laboratory Chemical Dynamics in Hydrocarbon Rich Atmospheres of Outer Planets

Investigating the formation of organic molecules in hydrocarbon rich atmospheres of planets and their moons is of paramount importance to understand the chemical composition, mixing ratios, and the future evolution of carbon bearing species in Solar System environments. The diacetylene molecule (C4H2) as detected in the stratosphere of Saturn and its moon Titan is the largest polyatomic organic species observed so far in the outer Solar System. In addition the methyl radical (CH3) together with methane (CH4), acetylene (C2H2), ethylene (C2H4), ethane (C2H6), methylacetylene (CH3CCH), propane (C3H8) and the CN bearing species hydrogen cyanide (HCN), dicyan (NCCN), methykyanide (CH3CN), cyanoacetylene (HCCCN), and presumably solid state dicyanoacetylene (NCC-CCN) were detected as well. Photochemical models of Jupiter, Saturn, Uranus, Neptune, Pluto and their satellites Titan and Triton predict further the presence of even more complex hydrocarbons up to triacetylene (C6H2) and tetraacetylene (C8H2). Previous experiments attempting to unravel the formation of these molecules in planetary environments employed and open reactors subjecting gas mixtures to high energy discharges or electron bombardments; often products were analyzed via gas chromatography coupled to a mass spectrometer (GS-MS). This approach can match the existence of major trace constituents. However, no information on radical intermediates could be supplied; further, possible open shell products and extremely labile products cannot be identified; hence involved reaction mechanism can only be guessed. However, the explicit identification of reaction intermediates, ALL reaction products, and the mechanism are a top priority to give a systematic picture on the chemistry in hydrocarbon rich atmospheres and to predict the formation of hitherto unobserved molecules.

Evaluation of anti-pyrene and anti-fluorene immunosorbent clean-up for PAHs from sludge and sediment reference materials followed by liquid chromatography and diode array detection

The determination of polycyclic aromatic hydrocarbons (PAHs) in complex matrices such as sludges or sediments was performed by off-line enrichment using four different immunosorbents (IS). These IS are anti-fluorene and anti-pyrene antibodies immobilized on silica. The method involves the extraction of PAHs from water samples onto either two anti-fluorene or two anti-pyrene IS followed by analysis using liquid chromatography with diode array detection (LC-DAD) and its validation using gas chromatography coupled to a mass spectrometer (GC-MS). The procedure also uses a solubilizer to limit unwanted adsorption on vessels or tubing. In order to be able to evaluate the four IS, we have analyzed environmental sediments and sludge reference materials containing PAHs. Sediments were extracted by sonication with dichloromethane–methanol (2∶1) and the extracts were brought up to a volume of 100 mL of water in order to perform the extraction with the anti-fluorene and anti-pyrene IS. This method was optimized for 13 of 16 PAHs included in the Environmental Protection Agency US (EPA) priority list. The selectivity of the IS cleanup and the LC-DAD spectra allowed a good identification and quantification in the analysis of sediment and sludge complex samples containing the priority PAHs established by the EPA. The results obtained with the four IS were compared after determination of PAHs in complex sewage sludge and sediment reference matrices. Moreover, clean-up using IS was compared with conventional clean-up procedures and showed a better selectivity for PAHs by the IS procedures.

On the odour of Tuber mesentericum

Odour composition of Tuber mesentericum s.l. has been studied by gas chromatography coupled to a mass spectrometer (GS-MS). 2-Methyl-1,3-butadiene and m -methyl anisole are two volatile metabolites that characterize the odour of this taxon.