901 resultados para GC-MS analysis


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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Natural oils have shown a scientific importance due to its pharmacological activity and renewable character. The copaiba (Copaifera langsdorffii) and Bullfrog (Rana catesbeiana Shaw) oils are used in folk medicine particularly because the anti-inflammatory and antimicrobial activities. Emulsion could be eligible systems to improve the palatability and fragrance, enhance the pharmacological activities and reduce the toxicological effects of these oils. The aim of this work was to investigate the antimicrobial activity of emulsions based on copaiba (resin-oil and essential-oil) and bullfrog oils against fungi and bacteria which cause skin diseases. Firstly, the essential oil was extracted from copaiba oil-resin and the oils were characterized by gas chromatography coupled to a mass spectrometry (GC-MS). Secondly, emulsion systems were produced. A microbiological screening test with all products was performed followed (the minimum inhibitory concentration, the bioautography method and the antibiofilm determination). Staphylococcus aureus, S. epidermidis, Pseudomonas aeruginosa, Candida albicans, C. parapsilosis, C. glabrata, C. krusei and C. tropicalis American Type Culture Collection (ATCC) and clinical samples were used. The emulsions based on copaiba oil-resin and essential oil improved the antimicrobial activity of the pure oils, especially against Staphylococcus e Candida resistant to azoles. The bullfrog oil emulsion and the pure bullfrog oil showed a lower effect on the microorganisms when compared to the copaiba samples. All the emulsions showed a significant antibiofilm activity by inhibiting the cell adhesion. Thus, it may be concluded that emulsions based on copaiba and bullfrog oils are promising candidates to treatment of fungal and bacterial skin infections

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The extraction with pressurized fluids has become an attractive process for the extraction of essential oils, mainly due the specific characteristics of the fluids near the critical region. This work presents results of the extraction process of the essential oil of Cymbopogon winterianus J. with CO2 under high pressures. The effect of the following variables was evaluated: solvent flow rate (from 0.37 to 1.5 g CO2/min), pressure (66.7 and 75 bar) and temperature (8, 10, 15, 20 and 25 ºC) on the extraction kinetics and the total yield of the process, as well as in the solubility and composition of the C. winterianus essential oil. The experimental apparatus consisted of an extractor of fixed bed and the dynamic method was adopted for the calculation of the oil solubility. Extractions were also accomplished by conventional techniques (steam and organic solvent extraction). The determination and identification of extract composition were done by gas chromatography coupled with a mass spectrometer (GC-MS). The extract composition varied in function of the studied operational conditions and also related to the used extraction method. The main components obtained in the CO2 extraction were elemol, geraniol, citronellol and citronellal. For the steam extraction were the citronellal, citronellol and geraniol and for the organic solvent extraction were the azulene and the hexadecane. The most yield values (2.76%) and oil solubility (2.49x10-2 g oil/ g CO2) were obtained through the CO2 extraction in the operational conditions of T = 10°C, P = 66.7 bar and solvent flow rate 0.85 g CO2/min

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The decontamination of the materials has been subject of some studies. One of the factors that it increases the pollution is the lack of responsibility in the discarding of toxic trash, as for example the presence of PCB (Polychlorinated Biphenyls) in the environment. In the Brazilian regulations, the material contaminated with PCB in concentrations higher than 50 ppm must be stored in special places or destroyed, usually by incineration in plasma furnace with dual steps. Due to high cost of the procedure, new methodologies of PCBs removal has been studied. The objective of this study was to develop an experimental methodology and analytical methodology for quantification of removal of PCBs through out the processes of extractions using supercritical fluid and Soxhlet method, also technical efficiency of the two processes of extraction, in the treatment of contaminated materials with PCBs. The materials studied were soils and wood, both were simulated contamination with concentration of 6.000, 33.000 and 60.000 mg of PCB/ kg of materials. Soxhlet extractions were performed using 100 ml of hexane, and temperature of 180 ºC. Extractions by fluid supercritical were performed at conditions of 200 bar, 70°C, and supercritical CO2 flow-rate of 3 g/min for 1-3 hours. The extracts obtained were quantified using Gas chromatography-mass spectrometry (GC/MS). The conventional extractions were made according to factorial experimental planning technique 22, with aim of study the influence of two variables of process extraction for the Soxhlet method: contaminant concentration and extraction time for obtain a maximum removal of PCB in the materials. The extractions for Soxhlet method were efficient for extraction of PCBs in soil and wood in both solvent studied (hexane and ethanol). In the experimental extraction in soils, the better efficient of removal of PCBs using ethanol as solvent was 81.3% than 95% for the extraction using hexane as solvent, for equal time of extraction. The results of the extraction with wood showed statistically it that there is not difference between the extractions in both solvent studied. The supercritical fluid extraction in the conditions studied showed better efficiency in the extraction of PCBs in the wood matrix than in soil, for two hours extractions the obtain percentual of 43.9 ± 0.5 % for the total of PCBs extracted in the soils against 95.1 ± 0,5% for the total of PCBs extracted in the wood. The results demonstrated that the extractions were satisfactory for both technical studied

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A implementação da espectrometria de massa (MS) para as análises de peptídeos (MS) e de aminoácidos (MS em tandem ou MS/MS) tornou possível a identificação de centenas de proteínas em experimentos únicos. Uma grande variedade de estratégias está disponível atualmente para o fracionamento e a purificação de amostras, a identificação de proteínas, a quantificação, a análise de modificações pós-traducionais (MPT's) e os estudos de interação. Dessa forma, a proteômica abre novas perspectivas na biologia de plantas com ênfase nos estudos de variabilidade genética, estresses fisiológicos e desenvolvimento de plantas.

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Turnera diffusa Willd. var. afrodisiaca (Ward) Urb. (syn. T aphrodisiaca) (Turneraceae) is a common aromatic plant growing wild in the subtropical regions of America and Africa. Its essential oil was studied by GC and GC-MS. Fifty-four components were characterized and identified, the most abundant being 1,8-cineol (11.4%), opoplenone (10.3%) cadalene (5.1%) and epi-cubenol (4.1%). Copyright (C) 2002 John Wiley Sons, Ltd.

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The presence of residues of the major groups of pesticides (organohalogen, organophosphorous, pyrethroids and organonitrogen) in representative samples of honey produced in Bauru (state of São Paulo, Brazil) was investigated from 1999 through2004. A multiresidue method was applied to honey samples to determine 48 pesticides with recoveries ranging from 76 to 95%. The limits of detection found were lower than 10 µg/kg for GC-MS-SIM. The results indicated that most pesticides found in the samples belonged to the organohalogen and organonitrogen groups. Residues of malathion were detected in almost all of the samples in high concentration.

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In last years it has talked a lot about the environment and the plastic waste produced and discarded. In last decades, the increasing development of research to obtain fuel from plastic material, by catalytic degradation, it has become a very attractive looking, as these tailings are discarded to millions worldwide. These materials take a long time to degrade themselves by ways said natural and burning it has not demonstrated a viable alternative due to the toxic products produced during combustion. Such products could bring serious consequences to public health and environment. Therefore, the technique of chemical recycling is presented as a suitable alternative, especially since could be obtain fractions of liquid fuels that can be intended to the petrochemical industry. This work aims to propose alternatives to the use of plastic waste in the production of light petrochemical. Zeolites has been widely used in the study of this process due to its peculiar structural properties and its high acidity. In this work was studied the reaction of catalytic degradation of high-density polyethylene (HDPE) in the presence HZSM-12 zeolites with different acid sites concentrations by thermogravimetry and pyrolysis coupled with GC-MS. The samples of the catalysts were mixed with HDPE in the proportion of 50% in mass and submitted to thermogravimetric analyses in several heating rates. The addition of solids with different acid sites concentrations to HDPE, produced a decrease in the temperature of degradation of the polymer proportional the acidity of the catalyst. These qualitative results were complemented by the data of activation energy obtained through the non-isothermal kinetics model proposed by Vyazovkin. The values of Ea when correlated to the data of surface acidity of the catalysts indicated that there is a exponential decrease of the energy of activation in the reaction of catalytic degradation of HDPE, in function of the concentration of acid sites of the materials. These results indicate that the acidity of the catalyst added to the system is one of the most important properties in the reaction of catalytic degradation of polyethylene

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PAHs (Polycyclic Aromatic Hydrocarbons) are a group of organic substances which receive considerable attention because of the carcinogenic and mutagenic properties of some of them. It is therefore important to determine the PAHs in different environmental matrices. Several studies have shown the use of gas chromatography coupled to mass spectrometry as a technique for quantification of PAHs by presenting excellent detection limits. This study aimed to develop an analytical methodology for the determination of 16 PAHs listed by the USEPA, test two methods for extraction of PAHs in water from a 23 factorial design, quantify them through the analytical technique coupled to gas chromatography mass spectrometry (GC/MS) using the method developed, and finally apply the results in chemometrics. The sample was synthesized and subjected to tests of the 23 factorial design, which has the factors: the type of extraction technique (ultrasound and digester), the ratio solvent / sample (1:1 and 1:3) and the type of solvent (dichloromethane / hexane and acetone / dichloromethane). The responses of eight combinations of the factorial design were obtained from the quantification by external calibration in GC/MS. The quantification method was developed from an optimized adaptation of the USEPA Method 8270. We used the full scan mode as a way of acquiring the mass spectra of 16 PAHs. The time in which the samples were subjected to ultrasound was fixed at 10 min and held an investigation to establish the conditions of power and time in the digester. We had the best response in the investigation of the digester power of 100 watts and the time of six minutes. The factorial design of liquid-liquid extraction showed that the most representative factors were: the use of the digester as extraction technique, the ratio solvent / sample 1:1 and the use of a 1:1 mixture of dichloromethane / hexane as a solvent more suitable. These results showed that the 1:1 mixture of dichloromethane / hexane is an excellent mixture to recover the extraction of PAHs an aqueous sample using the microwave digester. The optimization of the method of separation, identification and quantification of PAHs in the GC/MS was valid for 16 PAHs present in each chromatogram of the samples

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The use of essential oils in foods has attracted great interest, due to their antagonistic action against pathogenic microorganisms. However, this action is undesirable for probiotic foods, as products containing Lactobacillus rhamnosus. The aim of the present study was to measure the sensitivity profile of L. rhamnosus and a yogurt starter culture in fermented milk, upon addition of increasing concentrations of cinnamon, clove and mint essential oils. Essential oils were prepared by steam distillation, and chemically characterised by gas chromatography-mass spectrometry (GC-MS) and determination of density. Survival curves were obtained from counts of L. rhamnosus and the starter culture (alone and in combination), upon addition of 0.04% essential oils. In parallel, titratable acidity was monitored over 28 experimental days. Minimum inhibitory concentration values, obtained using the microdilution method in Brain Heart Infusion medium, were 0.025, 0.2 and 0.4% for cinnamon, clove and mint essential oils, respectively. Cinnamon essential oil had the highest antimicrobial activity, especially against the starter culture, interfering with lactic acid production. Although viable cell counts of L. rhamnosus were lower following treatment with all 3 essential oils, relative to controls, these results were not statistically significant; in addition, cell counts remained greater than the minimum count of 10(8)CFU/mL required for a product to be considered a probiotic. Thus, although use of cinnamon essential oil in yogurt makes starter culture fermentation unfeasible, it does not prevent the application of L. rhamnosus to probiotic fermented milk. Furthermore, clove and mint essential oil caused sublethal stress to L. rhamnosus.

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Three bradykinin-related peptides (nephilakinins-I to -III) and bradykinin itself were isolated from the aqueous washing extract of the capture web of the spider Nephila clavipes by gel permeation chromatography on a Sephacryl S-100 column, followed by chromatography in a Hi-Trap Sephadex-G25 Superfine column. The novel peptides occur-red in low concentrations and were sequenced through ESI-MS/MS analysis: nephilakinin-I (G-P-N-P-G-F-S-P-F-R-NH2), nephilakinin-Il (E-A-P-P-G-F-S-P-F-R-NH2) and nephilakinin-III (P-S-P-P-G-F-S-P-F-R-NH2)- Synthetic peptides replicated the novel bradykinin-related peptides, which were submitted to biological characterizations. Nephilakinins were shown to cause constriction on isolated rat ileum preparations and relaxation on rat duodenum muscle preparations at amounts higher than bradykinin; apparently these peptides constitute B-2-type agonists of ileal and duodenal smooth muscles. All peptides including the bradykinin were moderately lethal to honeybees. These bradykinin peptides may be related to the predation of insects by the webs of N. clauipes. (c) 2005 Elsevier B.V. All rights reserved.