Top PDF Airborne observations of formic acid using a chemical ionization mass spectrometer

Airborne observations of formic acid using a chemical ionization mass spectrometer

Airborne observations of formic acid using a chemical ionization mass spectrometer

The correct altitude profile is essential for satellite retrievals and their inference regarding the photochemistry of formic acid. A vertical profile of formic acid from 800 to 2300 m is shown in Fig. 8. The concentration increases up to 1200 m, peaking at a concentration of 313 pptv and then falling off with increasing altitude. Low concentrations were observed below 1000 m. Although Baboukas et al. (2000) observed emissions of formic acid from the ocean, net flux measure- ments are not well known. Emission rates during this flight may have been lower than the deposition rates, causing the observed lower concentrations. If the only source of formic acid was of primary origin from the surface, then, irrespec- tive of depositional losses, we would imagine that the highest levels would be encountered at the surface and the mixing ratios decrease with altitude. However, it is of course pos- sible to intercept polluted plumes at only higher altitudes and, relative to cleaner surface air, this would give rise to the observations reported. A further explanation of the peak observed at ∼ 1000 m is that there are significant secondary sources of formic acid, following oxidation of formic acid precursors within the plume. At 1000 m, air masses rising from anthropogenic and/or biogenic sources (primary and secondary) will be far less susceptible to dry deposition, and so it is possible to imagine that the formic acid altitude pro- file goes through a maximum at this altitude. A decrease in concentration is observed at 2000 m; this is effectively the top of the boundary layer, and this decrease may simply be dilution of these plumes. The profile in Fig. 8 was measured on the edge of the London plume. Despite the possible higher concentrations in the profile contributed by the plume, it can still provide information concerning the gas as a function of altitude, although it may not be typical of an ambient formic acid profile. Hence, the plume correlation between CO and HCOOH probably indicates that both primary emissions of HCOOH exist and also emissions of HCOOH precursors ex- ist in the urban environment.
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Detection of formaldehyde emissions from an industrial zone in the Yangtze River Delta region of China using a proton transfer reaction ion-drift chemical ionization mass spectrometer

Detection of formaldehyde emissions from an industrial zone in the Yangtze River Delta region of China using a proton transfer reaction ion-drift chemical ionization mass spectrometer

The measurements were carried out from 15 to 30 April 2015 on the campus of the Nanjing University of Information Sci- ence and Technology (NUIST). A detailed description of the site (32 ◦ 12 ′ 20.8 ′′ N, 118 ◦ 42 ′ 19.2 ′′ E) has been given in our previous work (please see Fig. 1 in Zheng et al. (2015a) for details). Briefly, the site was established by the Chinese Meteorological Administration as a training facility for me- teorological observations. Meteorology parameters, includ- ing wind direction, wind speed, ambient temperature, pres- sure, relative humidity, and solar radiation, were contin- uously measured according to Chinese national standards (GB31221-2014). The site was located in the middle of two highways, i.e., G40 and G205, which were about 1.3 km to the west and 1.5 km to the east of the site, respectively. From the aromatics measurement results, we found no substantial impacts on measured HCHO from traffic-related emissions, which will be detailed in the discussion section. When east- erly winds were dominant, the site was constantly affected by the outflow from the industry zone (Zheng et al., 2015a). All instruments were housed inside an air-conditioned trailer. The sample line was made of 6.4 mm OD PFA tubing and
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Constraining the sensitivity of iodide adduct chemical ionization mass  spectrometry to multifunctional organic molecules using the collision limit  and thermodynamic stability of iodide ion adducts

Constraining the sensitivity of iodide adduct chemical ionization mass spectrometry to multifunctional organic molecules using the collision limit and thermodynamic stability of iodide ion adducts

al., 2014). We compare the resulting sum total mass load- ings of all molecular components with the submicron or- ganic aerosol mass concentrations measured by an aerosol mass spectrometer (AMS) (DeCarlo et al., 2006). Applying the collision-limited sensitivity to all organic–iodide adducts to which we have not explicitly calibrated (vast majority of ions) results in a lower limit to mass concentrations measured by the FIGAERO HR-ToF-CIMS. Figure 5 shows the re- sult of this comparison for two different locations: (1) a pol- luted region in the southeast United States (Brent, Alabama), which is dominated by isoprene, and (2) a remote boreal for- est site (Hyytiälä, Finland) during springtime which is pre- dominantly influenced by monoterpene emissions. In both locations, the FIGAERO-HRToF-CIMS molecular composi- tion observations explain at least 50 % of the total AMS or- ganic mass. That is, based on our declustering scans and dis- tribution of binding enthalpies (e.g., Fig. 3c) from a similar chemical system (e.g., α-pinene ozonolysis in the presence of NO x ), we know that not all organic compounds are de-
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A switchable reagent ion high resolution time-of-flight chemical ionization mass spectrometer for real-time measurement of gas phase oxidized species: characterization from the 2013 Southern Oxidant and Aerosol Study

A switchable reagent ion high resolution time-of-flight chemical ionization mass spectrometer for real-time measurement of gas phase oxidized species: characterization from the 2013 Southern Oxidant and Aerosol Study

calibrations for as many of these compounds as possible will provide quantitative, spe- ciated data to modelers; it should be acknowledged that knowing the temporal behavior without quantification is also of importance. Even for the simple case of formic acid, cur- rent models cannot capture the observed diel cycle observed at SOAS with the known sources and sinks (Millet et al., 2015). Thus, it is questionable how providing a long list

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Caracterização mineralógica de solos tropicais por sensoriamento remoto hiperespectral.

Caracterização mineralógica de solos tropicais por sensoriamento remoto hiperespectral.

GALVÃO, L. S.; VITORELLO, I.; ALMEIDA FILHO, R. Effects of band positioning and bandwidth on NDVI measurements of tropical savannas. Remote Sensing of Environment, New York, v. 67, p. 181-193, 1999. GALVÃO, L. S.; VITORELLO, I.; FORMAGGIO, A. R. Relationships of spectral reflectance and color among near- and sub-surface horizons of tropical soil profiles. Remote Sensing of Environment, New York, v. 61, p. 24-33, 1997. GREEN, R. O. Retrieval of reflectance from AVIRIS- measured radiance using a radioactive transfer code. In: AIRBORNE VISIBLE/INFRARED IMAGING SPECTROMETER (AVIRIS) WORKSHOP, 3., 1991, Pasadena. Proceedings... Pasadena: Jet Propulsion Laboratory, 1991. p. 200-210. (Publication, 91-28). GREEN, R. O.; EASTWOOD, M. L.; SARTURE, C. M.; CHRIEN, T. G.; ARONSSON, M.; CHIPPENDALE, B. J.; FAUST, J. A.; PAVRI, B. E.; CHOVIT, C. J.; OLAH, M. R.; WILLIAMS, O. Imaging spectroscopy and the airborne visible/infrared imaging spectrometer (AVIRIS). Remote Sensing of Environment, New York, v. 65, p. 227-248, 1998.
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Kinetics and mechanism of the reaction of gold(III) chloride complexes with formic acid

Kinetics and mechanism of the reaction of gold(III) chloride complexes with formic acid

From the analysis of literature data [21, 22] it can be suggested that the change of acidity of the solution can affect the kinetics and mechanism of the gold(III) reaction reduction, leading under proper conditions to gold precipitation from the solution. In this paper we described the results of the kinetic studies of the reduction reaction of chloride gold(III) complex ions with formic acid in weak acidic solutions (pH = 2.9). We believe that the knowledge of the kinetics of gold(III) reduction reaction using formic acid can be a helpful in selection of the optimal conditions for selectivity of the reduction reaction of Au(III) ions in the presence of Pt(IV) and Pd(II) ions in the solution.
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Análise multirresíduos de pesticidas em tomate utilizando LC-MS/MS e avaliação dos...

Análise multirresíduos de pesticidas em tomate utilizando LC-MS/MS e avaliação dos...

Determination of pesticides in apple-based infant foods using liquid chromatography electrospray ionization tandem mass spectrometry. Journal of Agricultural and Food Chemistry,[r]

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Quím. Nova  vol.31 número3

Quím. Nova vol.31 número3

The injection and the extraction were completely automated using Prospekt-2 system and the method developed consisted of the following steps: the cartridge was solvated with 1 mL of methanol at 5 mL/min and equilibrated with 1 mL of water at same flow rate. Following the injection of 20 µL of the plasma sample into the cartridge, 750 µL of water at 2 mL/min were eluted, to retain etoricoxib and antipyrin, and waste plasma proteins. The cartridge was washed with 1 mL of water:methanol (95:5, v/v) at 2 mL/min, and then, eluted with mobile phase at 0.6 mL/min for 1 min to the analytical column and hence to MS/MS. After the elution and during LC-MS/MS run, the cartridge was washed with 2 mL of acetonitrile:water (50:50, v/v) at a flow rate of 2 mL/min. The autosampler was programmed to perform a wash of the needle with 500 µL of acetonitrile: 2% formic acid (50:50, v/v), to reduce carry- over, including one extra-wash step.
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Emprego da regressão linear simples na análise de mistura espectral

Emprego da regressão linear simples na análise de mistura espectral

proportionality relationship between a characteristic of the spectrum form and its quantity. In the case of hyperspectral images analysis the studies are focused on the features of diagnostic absorption of the elements. The procedures compare a feature spectral of reference with one of the image. The present work aims to evaluate the use of the linear regression simple in the spectral analysis. The linear regression can be elaborated of two forms considering the independent term as the reference spectrum or the image spectrum. The two functions present distinct behaviors in the abundance estimate. The distance relation between the two angular coefficients enables to verify the consistency of the information.
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Bisulfate – cluster based atmospheric pressure chemical ionization mass spectrometer for high-sensitivity (< 100 ppqV) detection of atmospheric dimethyl amine: proof-of-concept and first ambient data from boreal forest

Bisulfate – cluster based atmospheric pressure chemical ionization mass spectrometer for high-sensitivity (< 100 ppqV) detection of atmospheric dimethyl amine: proof-of-concept and first ambient data from boreal forest

is likely that other amines are detected with similar or lower sensitivity as DMA. Thus, we can report the lower limit con- centrations for other detected amines by applying the cali- bration coefficient obtained for DMA. Example mass spectra from (a) DMA/EA, (b) ammonia, (c) TMA/PA and (d) a C4- amine (e.g. DEA) are presented together with corresponding zero measurements in Fig. 9. Signals from DMA/EA and C-4 amine increase during zero gas flushing, while ammonia and TMA/PA show clear and moderate reduction upon zero mea- surement, respectively, the latter suggesting the presence of TMA/PA with concentrations larger than a few tens or hun- dreds of ppqV. However, for these extremely small signals, exact mass determination is not definitive; nor could the iso- topes be resolved from the background spectrum. Therefore, the identification of the compound as TMA/PA is not certain. Though the role of DMA in particle nucleation seems un- certain, the possible detection of TMA/PA leaves open the possibility that other amines might contribute to nucleation. Our result regarding [DMA] agrees with Schobesberger et al. (2015), suggesting sub-pptV DMA concentrations. How- ever, our values are in serious conflict with the concentrations of DMA/EA reported by Kieloaho et al. (2013). The reason could be that the entire signal in Kieloaho et al. (2013) was due to EA while we were completely insensitive to EA – for example, we could only detect DMA. However, it would be surprising that, while we obviously detect several amines, in- cluding DMA, MMA, TMA/PA and DEA (Fig. 2), the sensi- tivity for EA would be so poor. Another possibility could be in particle phase amine evaporation from the PTFE filter used to remove particulate matter from the sample in Kieloaho et al. (2013). Also, we performed our measurements at the open area of the measurement container field of SMEAR II, some 10–20 m from the uniform forested area, while Kieloaho et
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A compact PTR-ToF-MS instrument for airborne measurements of volatile organic compounds at high spatiotemporal resolution

A compact PTR-ToF-MS instrument for airborne measurements of volatile organic compounds at high spatiotemporal resolution

resolution (1–10 Hz) using a mass spectrometer (MS). Air- borne direct CIMS was pioneered by F. Arnold’s group in the mid-1980ies (Arnold and Hauck, 1985) and was fol- lowed by a breakthrough in the form of proton-transfer- reaction mass spectrometry (PTR-MS) (Crutzen et al., 2000). In the past 16 years, PTR-MS instruments have been suc- cessfully deployed on a variety of research aircraft, and the reader is referred to the thorough review by de Gouw and Warneke (2007) and the references given therein. The PTR- MS instruments that were hitherto flown on research aircraft used quadrupole filters for mass analysis. The quadrupole mass spectrometer (QMS) is usually operated in the selected ion monitoring (SIM) mode, i.e., a series of preselected m/z signals are sequentially measured for 0.5 to 1.0 s. For 10 analytes, it is this transfers into an overall time resolution of 5 to 10 s which causes the PTR-MS to be slower than most 1 Hz airborne air pollution sensors (e.g., O 3 , NO, NO 2 , CO,
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Mat. Res.  vol.16 número6

Mat. Res. vol.16 número6

This work examined the inluence of different chemical blowing agents (CBA), one endothermic and one exothermic, at the same concentration (2% by mass), on poly(acid lactic), PLA foams. The CBA was incorporated into the PLA in a single-screw extruder, and the foams were expanded by heating in an electric oven under free pressure conditions. Foam degradation in a simulated soil was performed according to the ASTM G160-03 standard. Changes in the physical-chemical, morphological and mechanical properties were used to evaluate the degradation. The results indicated that the different chemical blowing agents led to different mechanical and morphological properties for the foams, which resulted from the nature and decomposition rate of the blowing agents. Cells in the foams accelerated the degradation since they facilitated the iniltration of water toward the interior of the polymer and triggered the degradation process by hydrolysis.
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Diurnal variations of residential particulate wood burning emissions and their contribution to the concentration of Polycyclic Aromatic Hydrocarbons (PAHs)

Diurnal variations of residential particulate wood burning emissions and their contribution to the concentration of Polycyclic Aromatic Hydrocarbons (PAHs)

confirming that there are still many reasons to assume that wood combustion particles play a relevant role for indoor as well as outdoor particle exposure in areas where such combustion processes are relevant. As other combustion processes, wood burning emissions contain a variety of toxic pollutants and are thus expected to exert adverse effects upon human health. Different studies linked the contribution of wood combus-

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On line pre-concentration for simultaneous determination of low molecular weight organic acids and inorganic anions in Amazonian river water samples employing ion chromatography with conductivity detection

On line pre-concentration for simultaneous determination of low molecular weight organic acids and inorganic anions in Amazonian river water samples employing ion chromatography with conductivity detection

The IonPac AS11-HC and AS15 analytical columns in combination with the AG11 and AG15 guard column, respectively, are designed for the trace analysis of inorganic anions and low molecular weight organic acids in complex matrices using potassium hydroxide gradient elution. The first study consisted of testing the effects of the sample volume in the available columns AS11-HC and AS15 (250 x 4 mm i.d.) in order to monitor the organic acid and inorganic anion responses without any previous optimizations in the method. In general, the companies suggest that low sample volume should be inserted into AS11-HC column because of the overloading effect, while the AS15 column did not have this restriction. In this sense, different sample volumes were inserted varying from 200 to 500 µl with 5 µl cut volume into AS11-HC and full injection type varied from 500 to 2000 µl into AS15 column. Volumes above 2000 µl were not available because sample could contaminate the flush bottle through the transfer line, which had a volume of 2200 µl volume. Peak area results were observed using a reference solution containing 1.0 mg.l -1 organic and inorganic anions. This parameter control
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Discrimination of beer flavours by analysis of volatiles using the mass spectrometer as an electronic nose

Discrimination of beer flavours by analysis of volatiles using the mass spectrometer as an electronic nose

About 96% of the data variability is described by five principal components. Projection of the beer samples onto the plane defined by the first two PCs, which explain 90% of the variance, did not reveal any grouping of samples according to the beer brand. Therefore, other PCs were analyzed in order to discriminate the beers. Figure 2B shows the projection of the beer samples onto a plane de- fined by the PC1 and PC3 components, which, among the two-dimensional projections, provides the best separation of the samples studied. Marked sample clustering accord- ing to the beer brand is evident, although some groups are located close to each other or even partly overlap. The best results were achieved for beers 6, 7, and 8, which are well separated from the others. Clusters corresponding to beers 2 and 4, and 3 and 5 overlapped partially. Interest- ingly, beer 1, the only ale beer included in the data set, had PC1, PC2, and PC3 values very close to zero, as op- posed to the lager beers. This signifies that other principal components should be used to characterize and differ- entiate the ale beers, which have an essentially different set of major volatiles, when compared to lager beers.
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Mat. Res.  vol.15 número6

Mat. Res. vol.15 número6

where θ is the degree of surface coverage, k is the equilibrium constant of the adsorption process and C is the inhibitor concentration. The plots of C/θ versus C for mild steel corrosion in 20% formic acid for the three gemini surfactants at temperatures 30-60 °C are shown in Figure 3. A linear correlation of slope close to unity suggests that the adsorption of these surfactants on mild steel interface obeys Langmuir adsorption isotherm at all the temperatures studied. The equilibrium constant K, denotes the strength between the adsorbate and adsorbant. Large values of K imply more efficient adsorption and hence better inhibition efficiency 36 . K values are seen to increase with increase in
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J. Braz. Chem. Soc.  vol.28 número3

J. Braz. Chem. Soc. vol.28 número3

becomes an important tool when referring to the sensitivity and specificity of analytical methods. Furthermore, the possibility of different spectrum acquisition modes allows the enhancement of specificity and sensitivity of the method. For example, with the MRM (multiple reaction mode) acquisition mode, a determined ion is selected on the first analyzer (usually the protonated or deprotonated molecule), later this ion is fragmented in a collision cell and then the fragment ion, with a specific and characteristic m/z of the studied compound, is monitored in the last analyzer. 13
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Screening of Non- Saccharomyces cerevisiae Strains for Tolerance to Formic Acid in Bioethanol Fermentation.

Screening of Non- Saccharomyces cerevisiae Strains for Tolerance to Formic Acid in Bioethanol Fermentation.

Screening of yeast strains for stress and inhibitor tolerance is an important step in lignocel- lulosic bioethanol production. The utilization of only spot plate analysis for the identification of tolerance strains is easy to operate and has less equipment dependent, but is slow and time consuming [8]. Phenotypic Microarray (PM) is an integrated system for high-throughput screening of microorganisms. Compared with spot plate method, PM is a quick, automatic and liquid-culture based technique that allows screening of a large number of strains at the same time under various conditions [8, 23]. However, it relies on the measurement of cell respiratory activity rather than cell growth [8, 23]. PM has recently been used to characterize yeast toler- ance to various stresses, e.g. temperature, ethanol and inhibitors in the lignocellulosic hydroly- sate [19]. Seven non-Saccharomyces cerevisiae strains were screened using the phenotypic microarray. The results demonstrated that S. arboricolus 2.3319 and S. kudriavzeii IFO1802 could tolerate 20 mM formic acid (Fig 2). This agreed with results obtained using YNB spot plate method, as PM uses a minimal medium as well. Strain S. paradoxus DBVPG6466 could not tolerate 20 mM formic acid in PM experiments, suggesting that strains may have different acid tolerance abilities between solid culture (spot plate) and liquid culture (PM). This indi- cated that PM is a good complement to the traditional spot plate screening method.
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J. Braz. Chem. Soc.  vol.18 número5

J. Braz. Chem. Soc. vol.18 número5

In the second, third and fourth sample obtained by solubilization of the extract from E. vannamei in H 2 O, MeOH/H 2 O and acetonitrile/H 2 O, respectively, the nucleosides were not extracted in high amount compared with other compounds (see Figures 3B, 3C and 3D). It is possible that the clean up process of the extract using a Sepack-C 18 cartridge is necessary to retain these compounds that are not nucleosides, and also confirm the less polar characteristic of those.

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MEDIÇÕES DE VAPOR DE ÁGUA ATMOSFÉRICO E DA PRESSÃO DE SUPERFÍCIE A PARTIR DE IMAGENS DO SENSOR AVIRIS E SUA RELAÇÃO COM A TOPOGRAFIA NO COMPLEXO DE NIQUELÂNDIA Osmar Abílio de Carvalho Júnior1 ; Ana Paula Ferreira de Carvalho2 ; Renato Fontes Guimarães

MEDIÇÕES DE VAPOR DE ÁGUA ATMOSFÉRICO E DA PRESSÃO DE SUPERFÍCIE A PARTIR DE IMAGENS DO SENSOR AVIRIS E SUA RELAÇÃO COM A TOPOGRAFIA NO COMPLEXO DE NIQUELÂNDIA Osmar Abílio de Carvalho Júnior1 ; Ana Paula Ferreira de Carvalho2 ; Renato Fontes Guimarães

image is used to estimate the spatial distribution of water vapor and surface pressure. The study area was the massive Niquelândia presents a pronounced variation in height, with altitudes between 500m and 1.180m. A digital terrain model (DTM) was developed and compared with atmospheric images using linear regression. The condition of clear sky, without cloud cover, favored a high correlation between the DTM and the atmospheric parameters. The error images show the worst adjustments in water bodies and bare soil.

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