Pedro Afonso de Paula Pereira

Biodiesel: an overview

The importance of biodiesel production was analyzed based on scientific articles and patents. A critical analysis was presented on the most used oil sources, the catalysts and the methods to verify the transesterification yields. Also analyzed were the comparative studies on emissions from pure fossil diesel and mixtures with biodiesel in variable proportions. Finally some challenges and considerations focused on technological, agronomic and infrastructure aspects of biodiesel production were indicated.

Development, validation and application of a methodology based on solid-phase micro extraction followed by gas chromatography coupled to mass spectrometry (SPME/GC–MS) for the determination of pesticide residues in mangoes

A method was developed for the simultaneous analysis of 14 pesticide residues (clofentezine, carbofuran, diazinon, methyl parathion, malathion, fenthion, thiabendazole, imazalil, bifenthrin, permethrin, prochloraz, pyraclostrobin, difenoconazole and azoxystrobin) in mango fruit, based on solid-phase micro extraction (SPME) coupled to gas chromatography-mass spectrometry (GC-MS). Different parameters of the method were evaluated, such as fiber type, extraction mode (direct immersion and headspace), temperature, extraction and desorption times, stirring velocities and ionic strength. The best results were obtained using polyacrylate fiber and direct immersion mode at 50 degrees C for 30 min, along with stirring at 250 rpm and desorption for 5 min at 280 degrees C. The method was validated using mango samples spiked with pesticides at concentration levels ranging from 33.3 to 333.3 microg kg(-1). The average recoveries (n=3) for the lowest concentration level ranged from 71.6 to 117.5%, with relative standard deviations between 3.1 and 12.3%, respectively. Detection and quantification limits ranged from 1.0 to 3.3 microg kg(-1) and from 3.33 to 33.33 microg kg(-1), respectively. The optimized method was then applied to 16 locally purchased mango samples, all of them containing the pesticides bifenthrin and azoxystrobin in concentrations of 18.3-57.4 and 12.7-55.8 microg kg(-1), respectively, although these values were below the MRL established by Brazilian legislation. The method proved to be selective, sensitive, and with good precision and recovery rates, presenting LOQ below the MRL admitted by Brazilian legislation.

Determination of methanol and ethanol by gas chromatrography following air sampling onto florisil cartridges and their concentrations at urban sites in the three largest cities in Brazil

Abstract A new sampling protocol was developed to determine methanol and ethanol in the gas phase, at low concentration levels, in urban atmospheres. The procedure involves collection of air samples (20.0–30.0 l) with three florisil cartridges connected in series, at a flow rate ranging from 1.0 to 2.0 l min −1 and subsequent elution of the alcohols with water. Separation and quantification were done by gas chromatography (GC) coupled with a flame ionization detector, ‘SPI’ injector and column DB WAX (30 m×0.53 mm×1 μm). The minimum mass detected by the method, based on two times the average background mass on the blank cartridges, was 0.3 μg for both alcohols which, for a sampled volume of 30 l, resulted in detection limits of 7.6 and 5.3 ppbV for methanol and ethanol, respectively. The determined alcohol concentrations, in 42 different samples from the three largest cities in Brazil—Sao Paulo, Rio de Janeiro and Salvador—ranged from 72 ppbV to below the detection limit for methanol and from 355 to 12 ppbV for ethanol.

Measurements of semivolatile and particulate polycyclic aromatic hydrocarbons in a bus station and an urban tunnel in Salvador, Brazil

Motor vehicles constitute a significant source of polycyclic aromatic hydrocarbon (PAH) emissions to the atmosphere. Particle-phase priority pollutant PAH concentrations and total suspended particle mass (TSP) were measured in the Lapa bus station and the Americo Simas Tunnel, located in the city of Salvador, Brazil. Separate samples were collected at the bus station at different times of the day, including rush- and non-rush-hour periods. The highest concentrations for nearly all 16 priority PAHs measured at the bus station were observed at 18:30 h, with chrysene showing the highest mean value (26.6 ng m-3). The highest average PAH concentrations measured in the tunnel were observed for pyrene (79.4 +/- 11.5 ng m-3) followed by fluoranthene (39.0 +/- 5.2 ng m-3) and chrysene (28.0 +/- 4.17 ng m-3). TSP levels reached 423 micrograms m-3 in the bus station, and values as high as 2 mg m-3 in the tunnel. The measured Salvador tunnel PAH profiles are very similar to the Salvador bus station profiles, and are similar to PAH profiles reported for the Kojouike Tunnel, located in Kurashiki City, Japan, and the Caldecott Tunnel, located in Berkeley, California.

Compostos carbonílicos atmosféricos: fontes, reatividade, níveis de concentração e efeitos toxicológicos

In the last three decades carbonyl compounds, aldehydes and ketones, have received a great deal of attention due to their strong influence on photochemical smog formation and their recognized adverse human health effects. Carbonyl compounds are directly emitted into the atmosphere by combustion sources and also produced from photochemical oxidation of hydrocarbons and other organic compounds. In this paper it is presented a general overview about the carbonyl compounds sources, reactivity, concentration levels and toxicological effects.

Fatty Acid Esters of Triterpenes from Erythroxylum passerinum

O extrato hexânico das folhas de Erythroxylum passerinum alem de sitosterol, β-amirina, lupeol e eritrodiol, forneceu palmitato de β-amirina, palmitato de 3β,28-diidroxi-olean-12-enila (eritrodiol); palmitato de 3β,11β-diidroxi-olean-12-enila; palmitato de 3β-hidroxi-11-oxo-olean-12-enila e palmitato de 3β-hidroxi-11,12-epoxi-friedoolean-14-enila. As estruturas das substâncias foram estabelecidas atraves da analise dos seus dados espectrometricos, bem como de seus derivados transesterificados, utilizando-se tecnicas de RMN de 1H e de 13C, infravermelho e espectrometria de massas.

Quantification and source identification of atmospheric particulate polycyclic aromatic hydrocarbons and their dry deposition fluxes at three sites in Salvador Basin, Brazil, impacted by mobile and stationary sources

The present work has aimed to determine the 16 US EPA priority PAH atmospheric particulate matter levels present in three sites around Salvador, Bahia: (i) Lapa bus station, strongly impacted by heavy-duty diesel vehicles; (ii) Aratu harbor, impacted by an intense movement of goods, and (iii) Bananeira village on Mare Island, a non vehicle-influenced site with activities such as handcraft work and fisheries. Results indicated that BbF (0.130-6.85 ng m-3) is the PAH with highest concentration in samples from Aratu harbor and Bananeira and CRY (0.075-6.85 ng m-3) presented higher concentrations at Lapa station. PAH sources from studied sites were mainly of anthropogenic origin such as gasoline-fueled light-duty vehicles and diesel-fueled heavy-duty vehicles, discharges in the port, diesel burning from ships, dust ressuspension, indoor soot from cooking, and coal and wood combustion for energy production.

Headspace solid phase microextraction/gas chromatography-mass spectrometry combined to chemometric analysis for volatile organic compounds determination in canine hair: A new tool to detect dog contamination by visceral leishmaniasis

A new analytical methodology using HS-SPME/GC-MS was optimized in order to attain maximum sensitivity, using multivariate strategies. The proposed method was employed to evaluate the VOC profile exhaled from canine hair samples collected from 8 healthy dogs and from 16 dogs infected by Leishmania infantum. 274 VOCs were detected, which could be identified as aldehydes, ketones and hydrocarbons. After application of the Soft Independent Modeling of Class Analogy (SIMCA) and Principal Component Analysis (PCA) healthy and infected dogs, with similar VOCs profiles, could be separately grouped, based on compounds such as 2-hexanone, benzaldehyde, and 2,4-nonadienal. The proposed method is non-invasive, painless, readily accepted by dog owners and could be useful to identify several biomarkers with applications in the diagnosis of diseases.

An overview of the Rio de Janeiro Aerosol Characterization Study.

The Rio de Janeiro Aerosol Characterization Study was a joint U.S.-Brazilian project undertaken 1) to provide more complete information on the chemical composition of the wintertime Rio aerosol, with emphasis on its carbonaceous and sulfate components and 2) to compare the chemical composition of the Rio aerosol with those of urban U.S. aerosols. Concentration of inhalable (D50 = 15 μm) particulate matter (IPM) in Rio de Janeiro averaged 80.7 and 58.6 μg/m3 for day and night samples, respectively, at a site impacted by heavy motor vehicle traffic, during a wintertime sampling period. The average IPM concentration was higher than concentrations of IPM in many U.S. cities. Atmospheric concentrations of extractable organic matter (EOM) and polycyclic aromatic hydrocarbons were similar to those measured in eastern U.S. cities during the wintertime while organic and elemental carbon concentrations were somewhat higher than those reported for most urban aerosols in the United States. Concentrations of sulfate w...

Determination of carbonyl compounds in the atmosphere of charcoal plants by HPLC and UV detection

A chromatographic quantification method with two different mobile phases (elution conditions 1 and 2) was developed to determine carbonyl compounds (CCs) in air samples collected from charcoal production workplaces, using C18 cartridges coated with 2,4-dinitrophenylhydrazine (DNPHi). Several 2,4-dinitrophenylhydrazones (DNPHo) were separated and quantified using an HPLC system and UV detection. In 16 min, elution condition 1 successfully separated and quantified the DNPHo of 14 CC including acetaldehyde, acrolein, formaldehyde, and furfural, and estimated the sum of C4 isomers, butanal-isobutanal-butanone. This elution condition was able to resolve the pairs acrolein/furfural and propanone/propanal, which have been cited in the literature as difficult mixtures to be separated. The elution condition 2 allowed separation and quantification, in less than 30 min, of 13 out of the 17 CC listed above. This elution condition was also able to separate propanone from propanal and butanone from the other components of the C4 mixture. When the two mobile phases were used together, they allowed confirmation of the presence of the DNPHo in the real samples. Thus, both elution conditions have been shown to be appropriate to determine CC, in personal and stationary samples, collected in charcoal production plants.