Infrared laser ablation atmospheric pressure photoionization mass spectrometry

In this paper we introduce laser ablation atmospheric pressure photoionization (LAAPPI), a novel atmospheric pressure ion source for mass spectrometry. In LAAPPI the analytes are ablated from water-rich solid samples or from aqueous solutions with an infrared (IR) laser running at 2.94 μm wavelength. Approximately 12 mm above the sample surface, the ablation plume is intercepted with an orthogonal hot solvent (e.g., toluene or anisole) jet, which is generated by a heated nebulizer microchip and directed toward the mass spectrometer inlet. The ablated analytes are desolvated and ionized in the gas-phase by atmospheric pressure photoionization using a 10 eV vacuum ultraviolet krypton discharge lamp. The effect of operational parameters and spray solvent on the performance of LAAPPI is studied. LAAPPI offers ~300 μm lateral resolution comparable to, e.g., matrix-assisted laser desorption ionization. In addition to polar compounds, LAAPPI efficiently ionizes neutral and nonpolar compounds. The bioanalytical application of the method is demonstrated by the direct LAAPPI analysis of rat brain tissue sections and sour orange (Citrus aurantium) leaves.     

Visually observed mold and moldy odor versus quantitatively measured microbial exposure in homes

The main study objective was to compare different methods for assessing mold exposure in conjunction with an epidemiologic study on the development of children's asthma. Homes of 184 children were assessed for mold by visual observations and dust sampling at child's age 1 (Year 1). Similar assessment supplemented with air sampling was conducted in Year 7. Samples were analyzed for endotoxin, (1-3)-β-D-glucan, and fungal spores. The Mold Specific Quantitative Polymerase Chain Reaction assay was used to analyze 36 mold species in dust samples, and the Environmental Relative Moldiness Index (ERMI) was calculated. Homes were categorized based on three criteria: 1) visible mold damage, 2) moldy odor, and 3) ERMI. Even for homes where families had not moved, Year 7 endotoxin and (1-3)-β-d-glucan exposures were significantly higher than those in Year 1 (p < 0.001), whereas no difference was seen for ERMI (p = 0.78). Microbial concentrations were not consistently associated with visible mold damage categories, but were consistently higher in homes with moldy odor and in homes that had high ERMI. Low correlations between results in air and dust samples indicate different types or durations of potential microbial exposures from dust vs. air. Future analysis will indicate which, if any, of the assessment methods is associated with the development of asthma.     

Exposure to environmental tobacco smoke at work, at home, and during leisure time: a cross-sectional population sample

Environmental tobacco smoke (ETS) is among the most common environmental health risks, with a striking and immediate biological response and increased disease risk. Exposure studies have looked mostly at worksite or home exposures, whereas total exposure levels at the population level are rarely reported. This study examined ETS exposure at work, at home, and during leisure time in a cross-sectional population sample of working-age adults. Our aim was to monitor changes in ETS exposure from 1992 to 2002. More detailed information on duration of exposure, distribution of exposure sites, and patterns of exposure was obtained in 2002. Data were based on Finland's national population chronic disease risk-factor surveys (conducted every 5 years). Total sample size varied from 8,000 to 13,500. The survey includes a self-administered questionnaire about ETS exposure at different sites. The proportion of nonsmoking persons exposed to ETS declined throughout the study period among both men and women. In 2002, 5.9% of male and 3.6% of female nonsmokers were exposed to ETS 1 hour or more per day, whereas 5.8% of men and 1.7% women were exposed less than 1 hour daily. Worksite exposure was more common among younger age groups of both sexes, but nonsmoking women in older age groups received more exposure at home than at worksites. Policy developments on ETS should aim to protect the whole population from ETS in all environments given that health risks from ETS often persist at home and in leisure environments. Total exposure levels should be studied to assess the health impacts of ETS.     

Desorption atmospheric pressure photoionization

An ambient ionization technique for mass spectrometry, desorption atmospheric pressure photoionization (DAPPI), is presented, and its application to the rapid analysis of compounds of various polarities on surfaces is demonstrated. The DAPPI technique relies on a heated nebulizer microchip delivering a heated jet of vaporized solvent, e.g., toluene, and a photoionization lamp emitting 10-eV photons. The solvent jet is directed toward sample spots on a surface, causing the desorption of analytes from the surface. The photons emitted by the lamp ionize the analytes, which are then directed into the mass spectrometer. The limits of detection obtained with DAPPI were in the range of 56-670 fmol. Also, the direct analysis of pharmaceuticals from a tablet surface was successfully demonstrated. A comparison of the performance of DAPPI with that of the popular desorption electrospray ionization method was done with four standard compounds. DAPPI was shown to be equally or more sensitive especially in the case of less polar analytes.     

Induction Charging and Electrostatic Classification of Micrometer-Size Particles for Investigating the Electrobiological Properties of Airborne Microorganisms

Our earlier studies have shown that the electrostatic collection technique, a potentially "gentle" bioaerosol collection method, allows for efficient collection of airborne bacteria, but sensitive bacteria such as Pseudomonas fluorescens ( P. fluorescens ) lose their culturability during collection. We hypothesized that excessive stress was imposed on the sensitive bacteria by the sampler's conventional corona charging mechanism. In this research, we developed and built an experimental setup that allows us to analyze electrobiological properties of airborne microorganisms. In this experimental system, we imparted electric charges on airborne biological and nonbiological particles by aerosolizing them in the presence of an electric field. The charged P. fluorescens test bacteria and NaCl test particles were then channeled into a parallel plate mobility analyzer, which we have designed so that bacteria and inert particles carrying specific charge ranges can be extracted and made available for further analysis. When testing the experimental system, we related the extracted particle concentrations to the total particle concentration and obtained the charge distributions of these particles at different charging conditions. Our results have shown that even without charging, aerosolized P. fluorescens bacteria have a net negative charge and can carry up to 13,000 elementary charges per bacterium. In contrast, the NaCl particles were found to carry very few electric charges. We concluded that the electric charge carried by a bacterium consists of 2 components: its own natural charge, which can be high, and the charge imposed on it by the dispersion process. Our experiments have shown that the charge distributions on biological and nonbiological particles can be effectively manipulated by varying the external electric field during their aerosolization. Since airborne microorganisms may carry high internal electric charges, their collection by electrical field forces may be possible without first electrically charging them.     

Comparison of direct and alternating current vacuum ultraviolet lamps in atmospheric pressure photoionization

A direct current induced vacuum ultraviolet (dc-VUV) krypton discharge lamp and an alternating current, radio frequency (rf) induced VUV lamp that are essentially similar to lamps in commercial atmospheric pressure photoionization (APPI) ion sources were compared. The emission distributions along the diameter of the lamp exit window were measured, and they showed that the beam of the rf lamp is much wider than that of the dc lamp. Thus, the rf lamp has larger efficient ionization area, and it also emits more photons than the dc lamp. The ionization efficiencies of the lamps were compared using identical spray geometries with both lamps in microchip APPI mass spectrometry (μAPPI-MS) and desorption atmospheric pressure photoionization-mass spectrometry (DAPPI-MS). A comprehensive view on the ionization was gained by studying six different μAPPI solvent compositions, five DAPPI spray solvents, and completely solvent-free DAPPI. The observed reactant ions for each solvent composition were very similar with both lamps except for toluene, which showed a higher amount of solvent originating oxidation products with the rf lamp than with the dc lamp in μAPPI. Moreover, the same analyte ions were detected with both lamps, and thus, the ionization mechanisms with both lamps are similar. The rf lamp showed a higher ionization efficiency than the dc lamp in all experiments. The difference between the lamp ionization efficiencies was greatest when high ionization energy (IE) solvent compositions (IEs above 10 eV), i.e., hexane, methanol, and methanol/water, (1:1 v:v) were used. The higher ionization efficiency of the rf lamp is likely due to the larger area of high intensity light emission, and the resulting larger efficient ionization area and higher amount of photons emitted. These result in higher solvent reactant ion production, which in turn enables more efficient analyte ion production.     

Antioxidant, pro-oxidant and cytotoxic properties of parsley

Parsley (Petroselinum crispum) leaves were macerated with a mixture of methanol: water: acetic acid to produce a crude extract which was then defatted with (40°-60°) petrol. Antioxidant activity of the extract was evaluated using a battery of in vitro assays, viz., iron(iii) reduction, iron(ii) chelation and free radical scavenging assays. Evaluation of the pro-oxidant activity of the extract was based upon its effects upon DNA fragmentation and protein carbonylation. Cytotoxicity and apoptotic effects of the extract were determined in non-cancerous CV1-P fibroblast and cancerous A375 melanoma cells using MTT and LDH tests and caspase 3-like activity assay. The highest concentration, 2.0 mg ml(-1), decreased the viability of both cell lines, however, the cancerous melanoma cells were slightly susceptible to the effects. The observed cytotoxicity was not due to the caspase 3 activity. In conclusion, the toxicity might be explained by the pro-oxidative activity of components within the extract against proteins and/or DNA but it is not related to caspase 3-dependent apoptosis within cells.     

Emissions trading and investment decisions in the power sector—a case study in Finland

Organizations, which consider investment in or divestment of power production licences/capacity within the European Community, are exposed to the impacts of the European Union Emission allowance Trading Scheme (EU ETS). In this paper, the consequences of the EU ETS on investment decisions are explored in a country-specific setting in Finland. First, we review the general mechanisms through which the EU ETS influences size, timing and cashflows of an investment. Next, we discuss the projected changes in Finnish power producers’ investment environment and examine the financial impacts due to the EU ETS on a case investment decision, a hypothetical condensing power plant (250 MW_e). The standard discounted cash flow (DCF) analysis is extended to take into account the value of two real options: the option to wait and the option to alter operating scale. In a quantitative investment appraisal, the impact of emissions trading not only depends on the expected level of allowance prices, but also on their volatility and correlation with electricity and fuel prices. The case study shows that the uncertainty regarding the allocation of emission allowances is critical in a quantitative investment appraisal of fossil fuel-fired power plants.     

Cytotoxicity of curcumin,resveratrol and plant extracts from basil,juniper, laurel and parsley in SH-SY5Y and CV1-P cells

The health-promoting effects of natural phenolic compounds are attracting growing interest. In this study, we tested four plant extracts, namely basil, juniper, laurel and parsley, and two well-known pure phenolic compounds of natural origin, curcumin and resveratrol, for their possible cytotoxic effects in vitro. AraC was used as an apoptotic reference compound. The pure compounds were studied in two cell lines, SH-SY5Y neuroblastoma and CV1-P fibroblast cells, and the plant extracts in SH-SY5Y cells. Cytotoxicity was examined by MTT and LDH assays, and the molecular mechanisms by Western blot analysis of p53 protein in cells. Juniper extract decreased the cell viability and increased the amount of p53 in SH-SY5Y cells at lower concentrations than did other plant extracts, and its effects on the amount of p53 in cells were comparable to the treatment with 50 μM AraC. The actions of curcumin and resveratrol were dependent on the concentration and cell line. Curcumin decreased the cell viability and increased the amount of p53 in SH-SY5Y cells more effectively than in CV1-P cells. The comparison between the results of AraC and pure curcumin showed a similar effect on the amount of p53. Our results indicate a potential role of plant extracts and plant-derived compounds as health-promoting food constituents, as well as candidates for drug development.