Dual-Stage Consumable-Free Thermal Modulator for the Hyphenation of Thermal Analysis, Gas Chromatography, and Mass Spectrometry.

The design of the so-called "Peltier modulator" is presented. It is a new dual-stage consumable-free thermal modulator for thermal analysis-gas chromatography-mass spectrometry (TA-GC-MS). It requires only electrical power for operation as it facilitates thermo-electric coolers instead of cryogenics for trapping and resistive on-column heating for reinjection. Trapping and desorption temperatures as well as modulation cycles are freely adjustable. The stationary phase for the trapping region can be selected to suit the specific application, since common fused silica capillary is used. The Peltier modulator's performance is demonstrated with a broad range of different standard substances and with heavy crude oil as a complex real life sample. Successful modulation from n-pentane to pyrene (boiling points = 36/394 °C) is presented. The produced peaks show the narrowest bandwidths ever reported for a consumable-free thermal modulator, i.e., 12.8 ± 1.2 ms for n-pentadecane. The Peltier modulator is rugged, cost-effective, requires low maintenance, and decreases security issues significantly, compared to commercial available solutions using liquid N2/CO2.

Optically heated ultra-fast-cycling gas chromatography module for separation of direct sampling and online monitoring applications.

This work describes an ultrafast-cycling gas chromatography module (fast-GC module) for direct-sampling gas chromatography/mass spectrometry (GC-MS). The sample can be introduced into the fast-GC module using a common GC injector or any GC × GC modulator. The new fast-GC module offers the possibility to conduct a complete temperature cycle within 30 s. Its thermal mass is minimized by using a specially developed home-built fused silica capillary column stack and a halogen lamp for heat generation, both placed inside a gold-coated quartz glass cylinder. A high airflow blower enables rapid cooling. The new device is highly flexible concerning the used separation column, the applied temperature program, and the integration into existing systems. An application of the fast-GC module is shown in this work by thermal analysis coupled to gas chromatography-mass spectrometry (TA-GC-MS). The continuously evolving gases of the TA are modulated by a liquid CO2 modulator. Because of the rapid cycling of the fast-GC module, it is possible to obtain the best separation while maintaining the online character of the TA. Restrictions in separation and retention time shifting, known from isothermal and normal ramped fast-GC systems, are overcome.

Thermal Resilience of Imidazolium-Based Ionic Liquids-Studies on Short- and Long-Term Thermal Stability and Decomposition Mechanism of 1-Alkyl-3-methylimidazolium Halides by Thermal Analysis and Single-Photon Ionization Time-of-Flight Mass Spectrometry.

Ionic liquids are often considered as green alternatives of volatile organic solvents. The thermal behavior of the ionic liquids is relevant for a number of emerging large-scale applications at elevated temperature. Knowledge about the degradation products is indispensable for treatment and recycling of the used ionic liquids. The objective of this paper was an investigation of the short- and long-term stability of several 1-alkyl-3-methylimidazolium halides, determination of the degradation products, and the elucidation of their decomposition patterns and structure-stability relations. Short-term stability and mechanism of thermal degradation were investigated by a self-developed, innovative thermal analysis single-photon ionization time-of-flight mass spectrometry device with Skimmer coupling. The applied technology provides real-time monitoring of the forming species and allows tracing their change during the course of the decomposition. Therein, the almost fragment-free soft ionization with vacuum ultraviolet photons plays a crucial role. We have detected unfragmented molecules whose formation was only assumed by electron ionization. Nevertheless, the main decomposition products of the selected ionic liquids were alkyl imidazoles, alkenes, alkyl halides, and hydrogen halides. From the decomposition products, we have deduced the fragmentation patterns and discussed their interrelation with the length of the alkyl chain and the type of the halide anion. Our results did not suggest the evaporation of the investigated ionic liquids prior to their decomposition under atmospheric conditions. Long-term thermal stability and applicability were determined based on thermogravimetric analysis evaluated with a kinetic model. Thus, the time-dependent maximum operation temperature (MOT) for the respective ionic liquids has been calculated. As a rule, the short-term stability overestimates the long-term decomposition temperatures; the calculated MOT are significantly lower (at least 100 K) than the standardly obtained decomposition temperatures.

Environmental polycyclic aromatic hydrocarbons (PAHs) enhance allergic inflammation by acting on human basophils.

Diesel exhaust particles (DEPs) have been implicated in the worldwide increased incidence of allergic airway diseases over the past century. There is growing evidence that DEP-associated polycyclic aromatic hydrocarbons (PAHs) participate in the development and maintenance of immunoglobulin (Ig) E-mediated allergic diseases. To address this issue we investigated the impact of U.S. Environmental Protection Agency (EPA) priority PAHs as well as of PAH-containing airborne extracts on antigen-induced CD63 upregulation and mediator release from human basophils. Whole blood samples from birch pollen allergic and control subjects were incubated in the presence of organic extracts of urban aerosol (AERex) or EPA-PAH standard with or without rBet v 1. Basophils were analyzed for CD63 expression as a measure of basophil activation by using multiparameter flow cytometry. In addition, purified basophils from birch pollen allergic donors were incubated for 2 h in the presence of 1 muM benzo[a]pyrene (BaP) or phenanthrene (Phe) and then stimulated with rBet v 1 for 45 min. Supernatants were assayed for histamine, interleukin (IL)-4, and IL-8 by means of enzyme-linked immunosorbent assay (ELISA). Basophils exposed in vitro simultaneously to AERex or EPA-PAH standard and rBet v 1 expressed CD63 significantly more than with antigen alone. PAHs synergized with rBet v 1 dose dependently, but did not activate basophils from nonallergic donors. BaP and Phe significantly enhanced cytokine secretion (IL-4, IL-8) and histamine release from purified basophils without antigen added, and secretion was not further enhanced by rBet v 1 stimulation. In conclusion, PAHs from roadside emissions can directly activate sensitized basophils to cytokine secretion and drive proallergic processes through enhanced Fcepsilon RI-coupled mediator release from human basophils.

A minimal-invasive method for systemic bio-monitoring of the environmental pollutant phenanthrene in humans: Thermal extraction and gas chromatography - mass spectrometry from 1 mL capillary blood.

Phenanthrene is present in numerous environmental media and serves as a model substrate for the biomonitoring of polycyclic aromatic hydrocarbon (PAH). PAH exposure studies are commonly focused on urinary metabolites, concentrations of which are dependent on absorption, biotransformation and excretion. Monitoring of unmetabolized PAHs in blood would allow more reliable exposure assessment, but requires invasive sampling and extensive sample preparation. We describe the analysis of phenanthrene in 1µL capillary blood using thermal extraction (TE) combined with gas chromatography - mass spectrometry (GC-MS). Less invasive sampling of 1µL capillary blood does not require the assistance of medical staff. Compared to previous studies, analysis time was improved significantly by TE due to minimization of sample preparation steps. The evaluate method was applied successfully to the monitoring of phenanthrene blood levels. This is the first report presenting the pharmacokinetics of unmetabolized PAHs in human.

A systemic view on the distribution of diet-derived methanol and hepatic acetone in mice.

Volatile organic compounds (VOCs) from breath can successfully be used to diagnose disease-specific pathological alterations in metabolism. However, the exact origin and underlying biochemical pathways that could be mapped to VOC signatures are mainly unknown. There is a knowledge gap regarding the contribution of tissues, organs, the gut microbiome, and exogenous factors to the 'sum signal' from breath samples. Animal models for human disease such as mutant mice provide the possibility to reproduce genetic predisposition to disease, thereby allowing in-depth analysis of metabolic and biochemical functions. We hypothesized that breath VOCs can be traced back to origins and organ-specific metabolic functions by combining breath concentrations with systemic levels detected in different organs and biological media (breath, blood, feces and urine). For this we fed C57Bl/6N mice a grain-based chow or a purified low-fat diet, thereby modifying the emission of methanol in breath whereas acetone levels were unaffected. We then measured headspace concentrations of both VOCs in ex vivo samples of several biological media. Cecum content especially was identified as a likely source of systemic methanol, whereas the liver showed highest acetone concentrations. Our findings are a first step to the systemic mapping of VOC patterns to metabolic functions in mice because differences between VOCs could be traced to different sources in the body. As a future aim, different levels of so-called omics technologies (genomics, proteomics, metabolomics, and breathomics) could be mapped to metabolic pathways in multiple tissues, deepening our understanding of VOC metabolism and possibly leading to early non-invasive biomarkers for human pathologies.

Aerosol emissions of a ship diesel engine operated with diesel fuel or heavy fuel oil.

Gaseous and particulate emissions from a ship diesel research engine were elaborately analysed by a large assembly of measurement techniques. Applied methods comprised of offline and online approaches, yielding averaged chemical and physical data as well as time-resolved trends of combustion by-products. The engine was driven by two different fuels, a commonly used heavy fuel oil (HFO) and a standardised diesel fuel (DF). It was operated in a standardised cycle with a duration of 2 h. Chemical characterisation of organic species and elements revealed higher concentrations as well as a larger number of detected compounds for HFO operation for both gas phase and particulate matter. A noteworthy exception was the concentration of elemental carbon, which was higher in DF exhaust aerosol. This may prove crucial for the assessment and interpretation of biological response and impact via the exposure of human lung cell cultures, which was carried out in parallel to this study. Offline and online data hinted at the fact that most organic species in the aerosol are transferred from the fuel as unburned material. This is especially distinctive at low power operation of HFO, where low volatility structures are converted to the particulate phase. The results of this study give rise to the conclusion that a mere switching to sulphur-free fuel is not sufficient as remediation measure to reduce health and environmental effects of ship emissions.

Organic extracts of urban aerosol (< or =PM2.5) enhance rBet v 1-induced upregulation of CD63 in basophils from birch pollen-allergic individuals.

Epidemiological studies have linked the high prevalence rates of IgE-mediated allergic diseases to an increase in exposure to traffic-related air pollutants such as diesel exhaust particles (DEPs). There is growing experimental evidence that organic compounds of DEPs, predominantly polycyclic aromatic hydrocarbons (PAHs), participate in the development and maintenance of allergic airway diseases. In this study we investigated the impact of organic extracts of urban aerosol (AERex) containing various PAH concentrations on the activation of human basophils. Whole blood samples from six birch pollen-allergic and five control subjects were repeatedly incubated in the presence of AERex with or without recombinant Bet v 1 (rBet v 1). Basophils were analyzed for CD63 expression as a measure of basophil activation by using multiparameter flow cytometry. Basophils, when exposed in vitro to AERex and rBet v 1, expressed CD63 significantly more than with antigen activation alone. AERex synergized with rBet v 1 in a dose-dependent manner, but did not activate basophils from nonallergic donors. AERex effect on CD63 upregulation was found in blood samples of all patients and did not occur in the absence of rBet v 1. Strongest basophil activation was monitored upon stimulation with AERex comprising the highest PAH content. The capability of AERex to increase activation of basophils from birch pollen-allergic subjects at ambient concentrations suggests an important role of organic compounds of airborne particles in the aggravation of IgE-mediated allergic diseases. This could be a new aspect of regulation of unspecific promoting stimuli in clinical manifestation of allergic inflammation.

Determination of oxygenated polycyclic aromatic hydrocarbons in particulate matter using high-performance liquid chromatography-tandem mass spectrometry.

A high-performance liquid chromatography-tandem mass spectrometric (LC-MS/MS) method with a rapid and simple sample preparation was optimized and validated for the determination of phenanthrene-9,10-dione, chrysene-5,6-dione, benzo[a]pyrene-1,6-dione, benzo[a]pyrene-3,6-dione, benzo[a]pyrene-4,5-dione, benzo[a]pyrene-6,12-dione, benzo[a]pyrene-7,8-dione, benzo[a]pyrene-11,12-dione and 6-oxo-7-oxa-benzo[a]pyrene in particulate matter. The mass spectrometer was operated in the multiple reaction monitoring (MRM) mode leading to high sensitivity and selectivity. The limits of quantification (S/N=10) ranged from ca. 0.1 pg/microl to ca. 5.8 pg/microl and matrix dependent recoveries varied between 49 and 92%. The applicability of the LC-MS/MS method was shown by the analysis of particulate matter (PM(2.5)) collected during the course of 2005 in the Munich area, Germany. All oxy-PAHs determined exhibited higher mean and peak concentrations in the winter months compared to the concentration levels in the warmer season.

Breath gas monitoring during a glucose challenge by a combined PTR-QMS/GC×GC-TOFMS approach for the verification of potential volatile biomarkers.

Breath gas profiles, which reflect metabolic disorders like diabetes, are the subject of scientific focus. Nevertheless, profiling is still a challenging task that requires complex and standardized methods. This study was carried out to verify breath gas patterns that were obtained in previous proton-transfer reaction-quadrupole mass spectrometry (PTR-QMS) studies and that can be linked to glucose metabolism. An experimental setup using simultaneous PTR-QMS and complementary highly time-resolved needle trap micro extraction (NTME) combined with comprehensive 2D gas chromatography-time-of-flight mass spectrometry (GC×GC-TOFMS) was established for the analysis of highly polar volatile organic compounds (VOCs). The method was applied to the breath gas analysis of three volunteers during a glucose challenge, whereby subjects ingested a glucose solution orally. Challenge responsive PTR-QMS target VOCs could be linked to small n-carbonic (C2-C4) alcohols and short chain fatty acids (SCFA). Specific isomers could be identified by simultaneously applied NTME-GC×GC-TOFMS and further verified by their characteristic time profiles and concentrations. The identified VOCs potentially originate from bacteria that are found in the oral cavity and gastrointestinal tract. In this study breath gas monitoring enabled the identification of potential VOC metabolites that can be linked to glucose metabolism.

Particulate matter from both heavy fuel oil and diesel fuel shipping emissions show strong biological effects on human lung cells at realistic and comparable in vitro exposure conditions.

BACKGROUND: Ship engine emissions are important with regard to lung and cardiovascular diseases especially in coastal regions worldwide. Known cellular responses to combustion particles include oxidative stress and inflammatory signalling. OBJECTIVES: To provide a molecular link between the chemical and physical characteristics of ship emission particles and the cellular responses they elicit and to identify potentially harmful fractions in shipping emission aerosols. METHODS: Through an air-liquid interface exposure system, we exposed human lung cells under realistic in vitro conditions to exhaust fumes from a ship engine running on either common heavy fuel oil (HFO) or cleaner-burning diesel fuel (DF). Advanced chemical analyses of the exhaust aerosols were combined with transcriptional, proteomic and metabolomic profiling including isotope labelling methods to characterise the lung cell responses. RESULTS: The HFO emissions contained high concentrations of toxic compounds such as metals and polycyclic aromatic hydrocarbon, and were higher in particle mass. These compounds were lower in DF emissions, which in turn had higher concentrations of elemental carbon ("soot"). Common cellular reactions included cellular stress responses and endocytosis. Reactions to HFO emissions were dominated by oxidative stress and inflammatory responses, whereas DF emissions induced generally a broader biological response than HFO emissions and affected essential cellular pathways such as energy metabolism, protein synthesis, and chromatin modification. CONCLUSIONS: Despite a lower content of known toxic compounds, combustion particles from the clean shipping fuel DF influenced several essential pathways of lung cell metabolism more strongly than particles from the unrefined fuel HFO. This might be attributable to a higher soot content in DF. Thus the role of diesel soot, which is a known carcinogen in acute air pollution-induced health effects should be further investigated. For the use of HFO and DF we recommend a reduction of carbonaceous soot in the ship emissions by implementation of filtration devices.

A liquid chromatography-atmospheric pressure photoionization tandem mass spectrometric method for the determination of azaarenes in atmospheric particulate matter.

The development, optimization and validation of a liquid chromatography-atmospheric pressure photoionization tandem mass spectrometric (LC-APPI/MS/MS) method for the determination of 15 azaarenes (4-azafluorene, benzo[h] and -[f]quinoline, phenanthridine, acridine, 1-azafluoranthene, 4-azapyrene, benz[a]- and -[c]acridine, -10-azabenzo[a]pyrene, 7,9- and 7,10-dimethylbenz[c]acridine, dibenz[a,j]-, -[c,h] and [a,i]acridine) in airborne particulate matter is described. Each compound was detected and quantified operating in multiple reaction monitoring mode. Extraction of azaarenes was achieved using accelerated solvent extraction (ASE) with dichlormethane/methanol (50/50, v/v). After extraction, no additional clean-up procedure like solid phase or liquid/liquid extraction was necessary. Limits of quantification (S/Nx10) ranged from 0.2 pg/microl to 1.4 pg/microl, matrix dependent recoveries were between 57% and 94%, with relative standard deviations from 8% to 17%. Applicability of the method was demonstrated analyzing 10 samples of particulate matter (PM(2.5)) collected in winter 2008. In all samples dimethylbenz[c]acridines as well as dibenzacridines were below the limit of quantification, concentration of the remaining analytes were in the range from 0.002 ng/m(3) to 0.356 ng/m(3).

Differential impact of diesel particle composition on pro-allergic dendritic cell function.

Diesel exhaust particles (DEP) were described as potent adjuvant in the induction and maintenance of allergic diseases, suggesting that they might play a role in the increase of allergic diseases in the industrialized countries. However, the cellular basis by which these particles enhance allergic immune responses is still a matter of debate. Thus, we exposed immature murine bone marrow-derived dendritic cells (BMDC) to different particles or particle-associated organic compounds in the absence or presence of the maturation stimuli lipopolysaccharide (LPS) and analyzed the cellular maturation, viability, and cytokine production. Furthermore, we monitored the functionality of particle-exposed BMDC to suppress B cell isotype switching to immunoglobulin (Ig) E. Only highly polluted DEP (standard reference material 1650a [SRM1650a]) but not particle-associated organic compounds or less polluted DEP from modern diesel engines were able to modulate the dendritic cell phenotype. SRM1650a particles significantly suppressed LPS-induced IL-12p70 production in murine BMDC, whereas cell-surface marker expression was not altered. Furthermore, SRM1650a-exposed immature BMDC lost the ability to suppress IgE isotype switch in B cells. This study revealed that highly polluted DEP not only interfere with dendritic cell maturation but also additionally with dendritic cell function, thus suggesting a role in T(h)2 immune deviation.

Chemical investigation of eight different types of carbonaceous particles using thermoanalytical techniques.

The chemical composition of ambient aerosol particles affects numerous important aerosol parameters such as their hygroscopicity, optics, and mass as well as their potentially adverse health effects. The objective of this study was to derive both detailed chemical speciation and useful proxies for the quantitative classification of the organic matter (OM) content of carbonaceous aerosol samples. Using three different thermal desorption techniques in an inert atmosphere we investigated eight different carbonaceous particulate matter (PM) samples used for health effect studies: thermal desorption gas chromatography with mass spectrometry, evolved gas analysis with mass spectrometry, and thermogravimetry with Fourier transform infrared spectroscopy. The samples include different types of laboratory-generated particles (pigment black, diffusion flame soot, spark-generated carbon) and two ambient aerosol samples (diesel soot and particulates collected in a road tunnel). All samples showed increasing mass desorption with rising temperature, but no reliable OM classification was possible based on thermal mass desorption alone. In fact, the "organic-free" spark-generated carbon particles showed the second highest mass desorption at 800 degrees C due to the formation of oxygenated structures on unsaturated surface sites and the subsequent evolution of CO and CO2 at elevated temperatures. A quantitative OM classification was accomplished by combining measurements of thermogravimetry and mass spectrometry (up to 800 degrees C) into a novel parameter, the "apparent organic mass fraction". The validity of this classification was confirmed with a second proxy parameter, based only on the evolution of organic components during thermal desorption and information on the generation process of the particles. Both types of pigment blacks (Printex) samples and the spark-generated carbon particles showed the lowest apparent organic mass fraction (< 5%), whereas for road tunnel and diesel emission particles < 16 and < 19% was estimated, respectively.