Avaliação do desempenho analítico do método de determinação de TPH (Total Petroleum Hydrocarbon) por detecção no infravermelho

No presente trabalho os parâmetros de desempenho (validação intralaboratorial) da metodologia de determinação de TPH (Total Petroleum Hydrocarbons) foram determinados por detecção na região do infravermelho com o equipamento da Infracal TOG/TPH, visando aplicação em amostras de areia contaminadas com petróleo. Os ensaios foram realizados utilizando Óleo Marine Fuel 380, com densidade igual 0,987 g cm-3 e viscosidade de 5313 cP a 20°C. Este óleo foi fornecido pelo Centro de Pesquisa da Petrobrás (CENPES/PETROBRÁS/RJ), sendo o mesmo óleo derramado no acidente ocorrido em janeiro de 2000, na Baia de Guanabara, RJ, quando 1.300 m3 vazaram do duto que interliga a REDUC (Refinaria Duque de Caxias, RJ) ao terminal da Ilha d’Água/RJ, atingindo praias. Os resultados da validação indicaram que o desempenho da metodologia foi favorável à aplicação que se destina. Entre os parâmetros metrológicos obtidos neste trabalho, o limite de detecção do método foi de 4,06 mg L-1, consideravelmente inferior à faixa de concentração normalmente obtida para amostras em tais situações.

Validation of an analytical methodology for the quantitative analysis of petroleum hydrocarbons in marine sediment samples

This work describes a validation of an analytical procedure for the analysis of petroleum hydrocarbons in marine sediment samples. The proposed protocol is able to measure n-alkanes and polycyclic aromatic hydrocarbons (PAH) in samples at concentrations as low as 30 ng/g, with a precision better than 15% for most of analytes. The extraction efficiency of fortified sediments varied from 65.1 to 105.6% and 59.7 to 97.8%, for n-alkanes and PAH in the ranges: C16 - C32 and fluoranthene - benzo(a)pyrene, respectively. The analytical protocol was applied to determine petroleum hydrocarbons in sediments collected from a marine coastal zone.

Caracterização de amostras petroquímicas e derivados utilizando cromatografia gasosa bidimensional abrangente (GCxGC)

The goal of this article is to discuss the application of comprehensive two-dimensional gas chromatography (GCxGC) to petrochemical samples. The use of GCxGC for petroleum and petroleum derivatives characterization, through group type analysis, or BTEX (benzene, toluene, ethylbenzene, xylenes), total aromatic hydrocarbons, polyaromatic hydrocarbons, sulfur-containing, oxygen-containing, and nitrogen-containing compounds is presented. The capability of GCxGC to provide additional specific chemical information regarding petroleum processing steps, such as dehydrogenation of linear alkanes, the Fischer-Tropsch process, hydrogenation and oligomerization is also described. In addition, GCxGC analyses of petrochemical biomarkers and environmental pollutants derived from petrochemicals are reported.

Hidrocarbonetos e esterois como indicadores de fontes e destino de matéria orgânica em sedimentos da Baía de Sepetiba, Rio de Janeiro

The inputs of organic matter derived from natural and anthropogenic sources to Sepetiba Bay were investigated by using aliphatic hydrocarbons and sterols in superficial sediments. Concentrations ranged from 0.26 to 2.65 μg g-1, <0.01 to 17.41 μg g-1 and 0.77 and 9.24 μg g-1 for n-alkanes, UCM (unresolved complex mixture) and total sterols, respectively. The selected markers and ratios among individual compounds showed the major contribution of terrestrial sources to the total pool of sedimentary organic matter in the bay, but the accumulation of autochthonous organic matter increased with distance from the shoreline. The input of petroleum hydrocarbons and sewage (coprostanol in the range 0.01 to 0.43 μg g-1) were also detected, especially in the more urbanized regions of the bay, but at lower levels of contamination when compared to estuaries in other Brazilian coastal regions.

Potential of grasses and rhizosphere bacteria for bioremediation of diesel-contaminated soils

The techniques available for the remediation of environmental accidents involving petroleum hydrocarbons are generally high-cost solutions. A cheaper, practical and ecologically relevant alternative is the association of plants with microorganisms that contribute to the degradation and removal of hydrocarbons from the soil. The growth of three tropical grass species (Brachiaria brizantha, Brachiaria decumbens and Paspalum notatum) and the survival of root-associated bacterial communities was evaluated at different diesel oil concentrations. Seeds of three grass species were germinated in greenhouse and at different doses of diesel (0, 2.5, 5 and 10 g kg-1 soil). Plants were grown for 10 weeks with periodic assessment of germination, growth (fresh and dry weight), height, and number of bacteria in the soil (pots with or without plants). Growth and biomass of B. decumbens and P. notatum declined significantly when planted in diesel-oil contaminated soils. The presence of diesel fuel did not affect the growth of B. brizantha, which was highly tolerant to this pollutant. Bacterial growth was significant (p < 0.05) and the increase was directly proportional to the diesel dose. Bacteria growth in diesel-contaminated soils was stimulated up to 5-fold by the presence of grasses, demonstrating the positive interactions between rhizosphere and hydrocarbon-degrading bacteria in the remediation of diesel-contaminated soils.

Contaminação de aqüífero por hidrocarbonetos: estudo de caso na Vila Tupi, Porto Velho - Rondônia

Underground storage tanks (UST) are widely used in the Porto Velho area. A large number of these USTs are in bad condition due to corrosion processes causing groundwater contamination. A large number of these leaking underground fuel tanks (LUFT) are in urban areas but due to the lack of water quality monitoring, they are only detected when there is a high contamination level. This study identified petroleum hydrocarbons, derived from a LUFT, by a silica gel/petroleum ether partitioning gravimetric method and by gas chromatographic analysis of samples collected in wells dug in a gas station and in houses in the aforementioned neighborhood.

Determinação das formas de nitrogênio e nitrogênio total em rochas-reservatório de petróleo por destilação com arraste de vapor e método do indofenol

Several extraction procedures are described for the determination of exchangeable and fixed ammonium, nitrate + nitrite, total exchangeable nitrogen and total nitrogen in certified reference soils and petroleum reservoir rock samples by steam distillation and indophenol method. After improvement of the original distillation system, an increase in worker safety, a reduction in time consumption, a decrease of 73% in blank value and an analysis without ammonia loss, which could possibly occur, were achieved. The precision (RSD < 8%, n = 3) and the detection limit (9 mg kg-1 NH4+-N) are better than those of published procedures.

Removal of high-molecular weight polycyclic aromatic hydrocarbons

Alternatives for the removal of high-molecular weight polycyclic aromatic hydrocarbons (HWM-PAH) from soil were tested by adding fertilizer or glycerol, as well as the combination of both. Experiments were carried out for 60 days in reactors containing a HWM-PAH-contaminated soil (8030 μg kg-1), accompanied by pH monitoring, humidity control and quantification of total heterotrophic bacteria and total fungus. Fertilizer addition removed 41.6% of HWM-PAH. Fertilizer and glycerol in combination removed 46.2%. When glycerol was added individually, degradation reached 50.4%. Glycerol also promoted the increase of degradation rate during the first 30 days suggesting the HMW-PAH removal occurred through cometabolic pathways.

Straightforward synthesis of 2,2,4,4,5,7,7-d7-cholestane: a new deuterated standard in petroleum analysis

A short and efficient synthesis of heptadeuterated 2,2,4,4,5,7,7-d7-cholestane (1) from cholesterol (3) is described. The deuterated material will be useful for the analysis of different sources of petroleum in analytical geochemistry laboratories as internal standard for quantification of steranes via gas chromatography-mass spectrometry (GC-MS).

USE OF A LOW-COST TEMPLATE-FREE ZSM-5 FOR ATMOSPHERIC PETROLEUM RESIDUE PYROLYSIS

To understand the physicochemical properties and catalytic activity during the pyrolysis of atmospheric petroleum residue, a template-free ZSM-5 zeolite was synthesized using a direct method without additional seeds or an organic structure director and compared with conventionally synthesized ZSM-5. The crystallinities of the two zeolites were evaluated by XRD and FTIR and were quite similar; however, structural analyses using SEM and argon physisorption revealed that the zeolites diverged in particle diameter and in the external surface area of the micropores. The synthesis procedure without a template incorporated additional aluminum into the crystalline network, according to ICP-AES and TPD NH3 experiments. The catalytic pyrolysis performed over the template-free ZSM-5 generated results comparable to those for pyrolysis performed over the conventional ZSM-5 according to its hydrocarbon distribution. The selectivity to aromatics compounds was exactly the same for both ZSM-5 zeolites, and these values stand out compared to thermal pyrolysis. The template-free ZSM-5 produced 20% of light hydrocarbons (C4-C6), where such compounds are olefins and paraffins of great interest to the petrochemical industry. Therefore, template-free ZSM-5 is promising for industrial use due to its lowered synthesis time, low-cost and significant distribution to light hydrocarbons.

Reabilitação vocal pós-laringectomia total: resultados em longo prazo com prótese fonatória Blom-Singer® de longa permanência

Avaliar o uso em longo prazo de próteses fonatórias (PF) para reabilitação fonatória de pacientes submetidos à laringectomia total (LT). Foram estudados a influência do tempo de realização da punção tráqueo-esofágica (PTE), o uso de radioterapia pós-operatória (RTXpos-op), idade e seguimento do paciente, sobre a taxa de sucesso de uso da PF. FORMA DE ESTUDO: Clínico prospectivo. MATERIAL E MÉTODOS: Setenta e um pacientes submetidos à LT e reabilitados com PF de longa permanência. Todos foram avaliados por otorrinolaringologista e fonoaudióloga, quanto aos aspectos funcionais vocais, durante o seguimento. Os dados relativos a tempo de colocação da PF, tempo de utilização da PF, uso de RTXpos-op, idade do paciente, tempo de seguimento e tempo de duração de cada PF foram anotados. RESULTADOS: Houve 87% de pacientes com PTE primária e 13% com secundária. O tempo de seguimento variou de 12 a 87 meses, com média de 38 meses para a PTE primária e 51 meses para a secundária. Houve 59% de pacientes submetidos a RTXpos-op. A taxa de sucesso geral foi de 94%. Na PTE primária foi de 97% e na secundária 78% (p=0,07) e, após dois anos, foi de 96% na PTE primária e 75% na secundária (p=0,07). Utilização de RTXpos-op e idade do paciente não influenciaram no sucesso de utilização de PF, independentemente do tempo de seguimento. CONCLUSÕES: Houve tendência de maior sucesso na reabilitação vocal de pacientes submetidos à LT com a PTE primária. O uso de RTXpos-op e idade não influenciou nesta taxa de sucesso.

Recorrência na área do traqueostoma após laringectomia total

O desenvolvimento da recorrência na área do traqueostoma em pacientes laringectomizados é uma das evoluções mais sérias do carcinoma epidermóide de laringe. Os fatores mais comumente associados a esta patologia são a extensão infraglótica do tumor laríngeo e a traqueostomia prévia à laringectomia. OBJETIVO: Identificar achados de exame clínico de pacientes laringectomizados relacionados com a possível gênese desta recorrência. FORMA DE ESTUDO: Estudo descritivo retrospectivo. CASUÍSTICA E MÉTODOS: Foram analisados 47 pacientes laringectomizados em nosso hospital devido ao carcinoma epidermóide de laringe entre 1995 e 2004 e avaliado o número de recorrências, bem como os fatores de risco relacionados. RESULTADOS: A recorrência na área do traqueostoma desenvolveu-se em cinco (10,6%) destes pacientes. Não houve correlação estatística entre a invasão infraglótica do tumor ou traqueostomia prévia com a recorrência na área do traqueostoma. CONCLUSÃO: A recorrência na área do traqueostoma continua sendo uma das evoluções fatais do câncer laríngeo, não sendo possível neste estudo identificar fatores relacionados com esta recorrência. Novos estudos com casuísticas maiores e longos períodos de seguimento são necessários no futuro para melhor compreensão desta patologia.

Reabilitação fonatória do laringectomizado total: utilização de toxina botulínica na voz tráqueo-esofágica com prótese fonatória

Na punção tráqueo-esofágica(PTE) é realizada miotomia do músculo constritor da faringe, mas sua necessidade é entre 9% a 79% dos pacientes. Sua realização pode aumentar as taxas de fístula salivar no pós-operatório. A aplicação da TB é ambulatorial. OBJETIVO: Análise da eficácia da aplicação de toxina botulínica (TB), na reabilitação do laringectomizado total com voz tráqueo-esofágica(VTE) com espasmo(E) do segmento faringo-esofágico (SFE) sem miotomia. MATERIAL E MÉTODOS: Análise de oito pacientes submetidos à laringectomia total (LT), reabilitados com VTE com prótese fonatória (PF), esforço para emissão de voz devido à E do SFE. Todos submetidos a tratamento dessa alteração motora com injeção de 100 unidades de TB no SFE. A avaliação constituiu-se de análise perceptiva de voz, videofluoroscopia (VF) do SFE, análise acústica de voz e manometria computadorizada (MC) do SFE, todos antes e após aplicação de TB. DESENHO DE ESTUDO: Estudo prospectivo. RESULTADOS: Houve diminuição na pressão à MC do SFE, após a injeção de TB. Análise acústica demonstrou melhora na qualidade de harmônicos após o tratamento. Houve emissão de voz sem esforço e melhora do E após o uso da TB. CONCLUSÃO: Todos os pacientes com E do SFE apresentaram melhora vocal após aplicação da TB neste SFE.

Comparison of different methods for the determination of total organic carbon and humic substances in Brazilian soils

ABSTRACTAiming to compare three different methods for the determination of organic carbon (OC) in the soil and fractions of humic substances, seventeen Brazilian soil samples of different classes and textures were evaluated. Amounts of OC in the soil samples and the humic fractions were measured by the dichromate-oxidation method, with and without external heating in a digestion block at 130 °C for 30 min; by the loss-on-ignition method at 450 °C during 5 h and at 600 °C during 6 h; and by the dry combustion method. Dry combustion was used as reference in order to measure the efficiency of the other methods. Soil OC measured by the dichromate-oxidation method with external heating had the highest efficiency and the best results comparing to the reference method. When external heating was not used, the mean recovery efficiency dropped to 71%. The amount of OC was overestimated by the loss-on-ignition methods. Regression equations obtained between total OC contents of the reference method and those of the other methods showed relatively good adjustment, but all intercepts were different from zero (p < 0.01), which suggests that more accuracy can be obtained using not one single correction factor, but considering also the intercept. The Walkley-Black method underestimated the OC contents of the humic fractions, which was associated with the partial oxidation of the humin fraction. Better results were obtained when external heating was used. For the organic matter fractions, the OC in the humic and fulvic acid fractions can be determined without external heating if the reference method is not available, but the humin fraction requires the external heating.