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Edaphoclimatic conditions, planting altitudes, soil, the microbiome of plants and fruits, genotypes, and postharvest processing are variables that contribute to the chemical and sensory quality of the coffee. Thus, the objective of this study was to evaluate the impacts of planting altitude and fermentation of fruits on the chemical and sensory quality of the coffee using nuclear magnetic resonance (NMR) and linear discriminant analysis (LDA). Cherry coffees were harvested in 8 points of altitudes between 826 and 1078.08 meters. A completely randomized design with 8 planting altitudes, 5 fermentation processes, and 5 repetitions was performed. Lipids, trigonelline, citrate, and malate were the compounds that most contribute to the chemical discrimination of coffee in the altitudes below 969 m. While, in the high altitudes (> 1000 m), this discrimination was due to the HMF, quinic acid, caffeine, and formic acid and the global notes of coffee drink were higher than 80 points. In fermented coffee, the LDA of the chemical data indicates the formation of five clusters, showing how the compounds can suffer changes depending on the form of processing used in coffee. The best score was observed in samples of 1078.08 m and dry fermentation and only in 969 m was observed significant difference between spontaneous fermentation and induced fermentation. Thus, coffee sensory scores were dependent on planting and fermentation methods and NMR and LDA techniques proved to be important in chemical and sensory discrimination of coffees.

O café conilon (Coffea canephora), também conhecido como robusta, participa em torno de 25% do café produzido no Brasil. O melhoramento genético da espécie tem proporcionado um incremento substancial na qualidade final da bebida, por meio do lançamento de diversos materiais genéticos. Estes por sua vez apresentam uma grande diversidade na composição química, que impactam diretamente na qualidade do material genético. Portanto, é notório a importância de se ter em mãos ferramentas adequadas que tenham a capacidade de aferir de forma robusta esses parâmetros. Tendo isso em vista, o presente trabalho teve como objetivo testar a eficiência da técnica de espectroscopia do infravermelho para correlacionar possíveis relações entre propriedades genotípicas e os constituintes químicos do Coffea canephora. As matérias-primas selecionadas para a realização dos experimentos foram obtidas de três propriedades rurais no norte do Espírito Santo dos genótipos ‘02’ e ‘LB1’. Para análise físico-química foi utilizado a técnica de espectroscopia do infravermelho em conjunto com a análise discriminante por mínimo quadrados parciais (PLS-DA). A técnica de espectroscopia no infravermelho associada análise multivariada PLS-DA mostrou-se aplicável na identificação da composição química oriunda dos genótipos estudados. Os resultados da análise exploratória mostraram uma sutil separação dos genótipos ‘02’ e ‘LB1’ entre as propriedades testadas.

A cerveja e uma das bebidas alcoolicas mais antigas consumidas pela humanidade, tendo sido descoberta ha cerca de 7.000 anos. A bebida e composta por quatro ingredientes essenciais: agua, malte, lupulo e levedura. Quando consumida em quantidades moderadas, a cerveja pode trazer beneficios a saude semelhantes aos do vinho. Apesar da grande importância economica, cultural e cientifica que a cerveja possui, percebe-se a escassez de uma literatura em portugues voltada ao tema. Neste sentido, o presente trabalho tem como objetivo reunir informacoes presentes na literatura cientifica, apresentando os aspectos quimicos envolvidos na producao cervejeira, as tecnicas analiticas empregadas na caracterizacao da bebida, autenticacao e controle dos processos produtivos, assim como a atividade biologica que a cerveja possui. Dessa forma, na producao de cerveja sao observadas 5 etapas basicas, como a mostura, fervura, fermentacao, maturacao e envase, sendo avaliados na etapa final de producao o pH, acidez total, amargor, cor e teor alcoolico. Na identificacao dos compostos da cerveja, bem como na autenticacao e controle dos processos produtivos, as tecnicas analiticas utilizadas sao a espectroscopia na regiao do infravermelho (IV), ressonância magnetica nuclear de hidrogenio (RMN 1H), espectrometria de massas (MS) e cromatografia gasosa acoplada ao espectrometro de massas (CG-MS). Alem disso, estudos sobre as atividades biologicas de compostos presentes na cerveja revelam um potencial antioxidante, anti-inflamatorio, antimicrobiana, antitumoral, entre outros, ressaltando que o consumo moderado da bebida pode trazer beneficios na saude dos consumidores

The quality of the coffee is determined by the sensorial analysis, using subjective methods and it is known that this quality is related to the chemical constituents of the grains. The present study used infrared spectroscopy to correlate the chemical composition of the grain with the final quality of the product and to assist in the current evaluation method, generating more reliability in the process. This study applied the spontaneous and induced fermentationwith starter cultures (yeast) to evaluate the sensory potential from the impacts generated by the types of processes adopted. The experiments were conducted in a randomized block design with five replicates, in a 3x4 factorial scheme, with three fermentation times: 24, 48, and 72 hours and fourwet processes: Washed, Yeast fermentation, Fully washed without yeast, and Fully washed with yeast. Infrared spectra were taken in the medium region(FTIR-ATR) of the 34 samples generated by the treatments. Given that the method of determining the quality of coffee is subjective, based on scores given by cuppers, the FTIR-ATR spectra were used in the construction of chemometric models to predict sensory ratings given to the attribute ‘acidity’. Themean error of prediction of the model constructed for the sensory score was 0.11. Sensory results indicated a higher score for the acidity attribute, in dry fermentation with yeast at the time of 48 hours, suggesting a new strategy for the production of quality robusta coffee.Key words: Fourier transform infrared spectroscopy; chemometrics; fermentation; acidity.

This paper proposes a methodology to characterize the following petroleum properties: UOP characterization factor (K), nitrogen content, solubility parameter, sulfur content, maximum and minimum pour point, and kinematic viscosity (at 20 °C, 30 °C, 40 °C and 50 °C), in petroleum within a single 1H NMR (proton nuclear magnetic resonance) spectra. Multivariate calibration tools, such as partial least squares (PLS), orthogonal projections to latent structures (OPLS) (with variable selection), interval PLS (iPLS), synergy interval PLS (siPLS) and model population analysis (MPA), were applied to 138 samples. The models were evaluated by coefficient of determination (R2), root mean square error of prediction (RMSEP), and residuals. In general, model population analysis had better results in the determination of petroleum's physicochemical properties than PLS and OPS. Thus, MPA provided models with better accuracy in the determination of the following properties: UOP characterization factor (0.06), nitrogen content (0.048 wt%), kinematic viscosity at 40 °C (relative error of 21.9%) and pour point (14.58 °C and 19.2 °C, respectively). The sulfur content was estimated with a 0.09 wt% mean error of prediction, using the PLS model, and the solubility parameter with a 1.06 (MPa)1/2 mean error of prediction, using the OPLS model.

Random Forest (RF) technique has been shown to be promising in the supervised classification applied in different matrices. However, approaches to identifying significant variables that weight the model are scarce, in the classification problems. In this paper, we propose a methodology for the selection of variables of greater relevance in the construction of RF models. For the application of this methodology, classification models were developed to discriminating crude oil samples, about to their maximum pour point (MPP). In this sense, data from MPP (ASTM D5853) of 105 crude oil samples, their hydrogen (1H) NMR spectra and carbon (13C) NMR spectra were acquired. With MPP ranging from −54 °C to 39 °C, two classes were assigned: the first containing 43 samples with MPP value ≤ −9 °C, and, the second, 62 samples with MPP value > −9 °C. The 1H NMR models, with 90% accuracy, and 13C NMR, with 71% accuracy, were used in the selection of variable method. The results showed that the methodology proposed to select variables was effective in the distinction of the variables that best contributed to the discrimination of oils. Therefore, this new tool enabled a greater understanding of the interest chemical information, contained in the spectra and its relationship with the MPP property of the crude oil samples.

In this paper, monitoring of the physicochemical properties of crude oil blends during production stages is described. The data of the properties of crude oil blends were obtained by laboratory characterization, and then analyzed by principal component analysis (PCA), hierarchical cluster analysis (HCA), and Mahanalobis distance. Thus, the quality of the blends was monitored quickly with simple multivariate tools. The results indicate that a change in the contribution of different wells in the blends caused a change in the profile. The PCA demonstrated that in each period, the physicochemical properties in the blends contributed to verifying the spread of the data. The blends could be organized by HCA, and it was possible to identify outlier samples with different quality standards for the oil. This information is important because it allows checking the changes in the oil profile, which helps in making adjustments to improve the quality of the final product in the primary process.

Water-based drilling fluids are widely used in the petroleum exploration and production stage. After this stage, the residue contains several potentially polluting compounds, especially hydrocarbons. This waste is disposed of in industrial landfills for treatment, thus raising industrial operational costs. A combination developed of the residual oil from water-based drilling fluid waste. Relevant parameters were temperature, centrifugal force and the use of synthetic and natural polymers. Results showed that an increase in centrifugal force and temperature are essential for separation of the oil phase. The use of polymers improved efficiency by completely removing the oil from the residue, around 20% v/v. The characterization of the recovered oil classified it as light oil with density at 20 °C of 0.7997 g·cm−3 and API gravity of 44.4, low sulfur content (0.0667 wt%), total acid number of 0.812 mg of KOH g−1, water content of 0.58% v/v and saturated, aromatic and polar contents of 64.11, 5.19 and 30.70 wt%, respectively. These results show that is possible to recover a viable oil that can be incorporated at the midstream stage, thus avoiding disposal and reducing operational costs and environmental impact.

Because the methods specified by regulatory agencies for the determination of the physicochemical properties of biodiesel can be laborious and expensive, the development of alternative methodologies represents a major breakthrough. Thus, low-field nuclear magnetic resonance (NMR) is an advantageous option because it is nondestructive and reduces the cost and time consumption. In this study, the partial least squares (PLS) regression method was used to create models that correlated the decay curves of the Carr–Purcell–Meiboom–Gill (CPMG) signal, obtained from low-field NMR equipment (2.2 MHz for 1H), with the kinematic viscosity, specific mass and refractive index of biodiesel and their blends. Seventeen oilseeds diversified between edible and non-edible oils were utilized to synthesize the biodiesel and produce binary blends. Separately, multivariate calibration models were created only with biodiesel and blends with castor bean because these samples showed different tendencies from the others. The values of root mean square error of prediction (RMSEP) for the kinematic viscosity, specific mass and refractive index were equal to 0.1 mm2·s−1, 3.7 kg·m−3 and 0.002, respectively, for samples of biodiesel and blends without castor bean and 0.6 mm2·s−1, 2.0 kg·m−3 and 0.0005 for samples of biodiesel and blends with castor bean. The results reveal that the developed models are very satisfactory to predict the quality parameters of biodiesel and blends based on CPMG data with fairly good efficacy.

COMPARING THE PERFORMANCE OF TWO MASS ANALYZERS (FT-ICR MS & LTQ MS): AN EXPERIMENTAL CLASS ON ANALYSIS OF ORGANIC COMPOUNDS. Mass spectrometry (MS) is a high-performance analytical technique that allows a measurement of the mass/charge (m/z) ratio of compounds present in a sample. MS is able to separate two m/z ions with determined values (mass resolution), being an important characteristic, especially in the analysis of biochemical components and complex mixtures. Mass analyzers define the resolving power and accuracy of different types of mass spectrometers. Herein, the performance of two mass analyzers (Fourier Transform Ion Cyclotronic Resonance (FT-ICR) and quadrupole ion trap (LTQ)) was tested on low (Mw = 165-679 Da) and high (Mw = 783-8.58 kDa) molecular weight molecules (Phenacetin, Procaine, Benzocaine, Caffeine anhydrous, Lidocaine, two metal porphyrin standards, the first cobalt and the second vanadium, and two protein standards, Ubiquitin and Beauvericin), and finally, for an oil sample. LTQ-MS and FT-ICR-MS had similar performance and high reproducibility. However, the mass accuracy and resolution power of the FT-ICR (error lower than 5 ppm and RP higher than 400,000) was higher, being therefore, it was more suitable for the analysis of proteins and oil, for instance. On the other hand, the CID analysis via LTQ demonstrated its applicability in fragmentation experiments, being able to determinate the chemical connectivity of organic compounds in non-complex mixtures.

The main types of hydrate inhibitors are thermodynamic (THI), kinetics (KHI) and anti-agglomerants (AA) inhibitors. Kinetic inhibitors are used in low dosages but do not have satisfactory efficiency in large subcoolings. On the other hand, thermodynamic inhibitors are widely used in the industry and require high dosages. In order to study a combined inhibition, the behavior of three different commercial kinetic inhibitors combined with ethanol (THI) was tested under subcooling conditions in cases which unique kinetic inhibition did not yield satisfactory results. With 3% concentrations of kinetic inhibitors and a 10% by mass ratio of ethanol, it was possible to identify a significant increase in induction time for two of the inhibitors tested. Once the growth of the hydrate crystals began to appear, the presence of inhibitors did not result in significant gain in delaying the crystallization process. Some physical characteristics of the formed hydrates were altered in the presence of kinetic inhibitors and ethanol, evidencing a lower capacity of the crystals to adhere. With the same concentration of kinetic inhibitor and a 30% by mass ratio of ethanol the KHI presented low effectiveness.

Water-in-oil (W/O) emulsions are present in applications from well drilling to refining and cause diverse problems. The present paper details the results of a study of the stability and homogeneity of W/O emulsions of a heavy oil using the optical microscopy technique. The W/O emulsions used previously dehydrated heavy oil with the addition of increasing volumes of 10, 20, 30, 35 and 40% w/v of deionized water and formation water, under mechanical stirring at 2500, 5000, 10,000 and 15,000 rpm. Moreover, a saturated sodium chloride solution was added to the oil in the contents at 10, 20 and 30% w/v under stirring at 5000 rpm, in order to verify the influence of the electrolyte type on the stability of the emulsions. The W/O emulsions were subjected to a gravitational separation test to verify stability and photomicrographs of the emulsions were analyzed to evaluate the homogeneity and the droplet size distribution (DSD). The results showed that the prepared emulsions were stable and homogeneous even after aging for 30 days and after being subjected to heating. This stability may be related to the high content of resins and asphaltenes in the studied oil. The emulsions prepared with formation water showed higher DSD values than those prepared with saturated NaCl solution and deionized water. This distinction of droplet sizes can be related to the presence of ions of different charges in the formation water.

Determining the physicochemical properties of petroleum is important for rapid decision-making during the production process. True boiling point (TBP) curve is the most important parameter in the petroleum characterization. However, the TBP can be estimated by high temperature gas chromatography (HTGC). In this paper, the HTGC technique associated with PLS regression was used to estimate API gravity, kinematic viscosity, pour point, carbon residue, saturated and aromatic content in crude oil. We use 98 samples with API gravity ranging from 11.4 to 54.0. Afterwards the developed methods were applied in nine samples from a field of production of the Brazilian coast. PLS model for API gravity, carbon residue, saturates and aromatics contents show root mean square error of prediction (RMSEP) set of 1.7, 0.83 wt%, 6.76 wt% and 4.05 wt% respectively. These models were applied to the nine samples and presented an exact equivalent to the models developed. The models for logarithm of kinematic viscosity and pour point show RMSEP of 0.31 and 12 °C respectively. Furthermore, tests applied in all models for evaluating the presence of systematic and trend errors indicate that there are no significant evidences of the presence of these types of error in the residues, at significance level of 5%.

The presence of hydrogen sulfide (H 2 S) poses many challenges in the production of petroleum at all stages of crude oil refinement and processing. Injection of an H 2 S scavenger into the hydrocarbon stream is most commonly used to reduce the concentration of H 2 S. Several H 2 S scavengers are commercially available, but each one must be examined to determine its suitability in terms of efficiency for capturing sulfide in petroleum. Therefore, in the present work, we proposed a system and process (hereinafter denoted as experimental setup/design) to test various H 2 S scavengers for their ability to efficiently capture sulfide in petroleum. To accomplish this, 46 samples of commercial H 2 S scavengers were tested using spectroscopy in the infrared region in association with Principal Component Analysis. It was concluded that samples with extreme pH and absorbance band intensity at 1175 cm −1 greater than 0.095 showed the best efficiency for capturing sulfide in petroleum and that success of competing scavengers could be predicted based on these parameters.

Brazilian oil production of pre-salt layer consists of oils with high content of saturated compounds. The identification of paraffinic and naphthenic compounds in these crude oils is key to understanding their rheological behavior. In the present study, comprehensive two-dimensional gas chromatography was performed to assess the greater separation capacity of products when compared with one-dimensional gas chromatography. Accordingly, it was possible to estimate relative the various classes existing in the saturated fraction of the crude oil. The results indicate that naphthenic compounds (53-77%) are more abundant than n-paraffins and iso-paraffins (22-46%) in nonpolar petroleum fractions from medium to low gravity, according American Petroleum Institute (API). Light oils showed high amount of iso-paraffins (37%), and the second most abundant class was the monocyclic compounds (30%). Crude oils with high pour point showed higher amount of heavy n-paraffins than oils with low pour point, suggesting a correlation between pour point and high molecular weight n-paraffins.

This paper reports the droplet size distribution (DSD) measurements in 28 W/O (water/oil) crude oil emulsions prepared with two Brazilian oils (medium and heavy) under different shear conditions using both 10 g L-1 NaCl solution and water production by low field nuclear magnetic resonance (NMR, 2.2 MHz). The PFGSTE (pulsed-field gradient-stimulated echo) pulse sequence applied was able to separate the crude oil emulsion signal for both medium and heavy oil even for low dispersed phase content (1.51 wt.%) and took into account only the aqueous phase signal. All emulsions exhibited an average diameter smaller than 5.5 µm because of the severe shear conditions. Despite the difficult processing of the S24 (6.48 wt.%) emulsion signal, good agreement was achieved between low field NMR and low-angle laser light scattering (LALLS) results. Finally, the paramagnetic ions in the water production did not affect the NMR measurements, demonstrating its applicability for analyzing real emulsions.

This paper describes pour point behavior of three heavy oils with the addition of kerosene, turpentine, toluene and gas condensate. The study showed a decrease in the pour point of all oils that relates with the oil chemical composition. The oil with lower API gravity (higher amount of asphaltenes and resins) showed higher pour point decay for all solvents, highlighting gas condensate and turpentine. The use of gas condensate to reduce the pour point of heavy oils is particularly advantageous, when available in the oilfield. Prevent the stoppage in the oil production, due to clogging and flow problems in the pipelines, and facilitate the logistics, reducing process operational costs

Although, estuarine ecosystems have an ecological and economical importance as they have a high biological productivity and occur within a unique and dynamic environment, they have been subjected to anthropogenic alterations. The Great Vitória Estuarine System (GVES), Espírito Santo State, Brazil, is not an exception, as urbanization is growing around it with a high quantity of sewage been added to the system. In order to evaluate the eutrophication state as well as the meiofauna response to it, several parameters in both sediments and in the water column were assessed. Orthophosphate, nitrite, nitrate, ammonia, chla and Fecal Coliform counts (FC) ranged from 0.2 to 3.2 μM, 0.25 to 1.14 μM, 1.83 to 0.19μM, 4.19 to 49.23 μM, 0.61 to 6.72 μg/L and 14 to 5.0x104 MPN/100 mL of water, respectively. These results showed that the GVES is under an eutrophication process and that the Passagem Channel experienced the largest impacts. Sewage plays an important role in this eutrophication process as indicated by PCA and correlations tests. The density of meiofauna showed similar values to those found in environments with similar levels of anthropogenic stress. This multi-approach evaluation revealed several aspects of the impacted estuary and could be used as an important tool to manage better the estuary.

The commercially available biodiesel in Brazil is a mixture formed by two different raw materials: oleaginous plants and animal fats. Methanol is the alcohol commonly used in the transesterification of triglycerides, however, due to high ethanol production in Brazil, it can be used by manufacturers, producing a complex commercial blend. In this paper, the biodiesel content in diesel was evaluated using the hydrogen nuclear magnetic resonance (1H NMR) technique associated with univariate and multivariate calibrations. Two univariate models were evaluated. The first one used the ratio of area of the signals of olefins to aliphatics, and the second used the ratio of the area of the signals of the methyl group from the ester to the aliphatics. The multivariate model was constructed using partial least squares (PLS) regression. The results show that using the area of the signals related to the olefins method presented an accuracy similar to the PLS model. However, the multivariate method has a better analytical sensitivity and lower limits of detection and quantification. Using only part of the 1H NMR spectrum to construct the model can be less efficient than using a broader set of information encompassing the full spectrum.

Data fusion from different analytical sources can be a feasible way to estimate physicochemical properties of petroleum when compared to using a single analytical technique. This occurs because outputs of different instrumental techniques can carry complementary information and act synergistically during calibration. In this paper, we investigate the potential of data fusion strategies for estimating seven crude oil properties: sulphur content (S), total nitrogen content (TN), basic nitrogen content (BN), total acid number (TAN), saturated (SAT), aromatic (ARO) and polar (POL) contents. We used 127 crude oil samples split into 70% for calibration and 30% for prediction. Partial least squares (PLS) regression models were constructed from Fourier transform mid-infrared (FTIR) and 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. Data fusion models were built: fused at low and mid-level in different combinations. While mid-level fusion usually increased the accuracy of models, low-level fusion caused insignificant improvements. Using PLS mid-level fusion, we estimated S, TN, BN, TAN, SAT, ARO and POL contents with average prediction errors of 0.064 wt%, 0.049 wt%, 0.0070 wt%, 0.16 mgKOH·g−1, 5.34 wt%, 3.66 wt% and 6.58 wt%, respectively, with coefficients of determination equal to 0.87, 0.78, 0.98, 0.91, 0.79, 0.67 and 0.63 for the prediction set and using 4, 3, 3, 3, 2, 4 and 2 latent variables, respectively. Although promising results were obtained, mid-level fusion demonstrates to be the best strategy usually improving accuracy of models.

In this paper, a 400 ppm aqueous solution of guar gum polysaccharide was submitted to a turbulent flow regime in order to monitor molecular degradation and drag reduction. Guar gum samples were isolated and analyzed by spectroscopic, thermoanalytical and viscosimetric techniques. The drag reduction promoted by guar gum is compromised as the polysaccharide undergoes degradation. Viscosimetric analysis of guar gum showed a reduction in viscous molecular mass. Mid-infrared spectra and hydrogen nuclear magnetic resonance suggest that mechanical degradation promotes hydrolysis of the glycosidic bond α (1 → 6) releasing ( d )-galactose owing to the appearance of the carbonyl functional group. Thermal analysis revealed the reduction of the polysaccharide's thermal stability by reduction of the polymer chain. A comprehensive analysis of these combined parameters affords a foundation for the development of more efficient biopolymers in the context of improved drag reduction.

Guar gum is used in low concentrations as a drag reducing agent in turbulent flows to significantly accelerate flow in oil pipelines, oil well operations and aqueous systems. Drag reduction also promotes a decrease in energy demand in pumping systems. However, the polymers undergo mechanical degradation and lose the ability to promote drag reduction over time. In this paper, the drag reduction, the power required by the pumps and the degradation of the guar gum were evaluated during a turbulent flow of an aqueous solution containing the biopolymer. The results indicate the mechanism of degradation of guar gum by the hydrolysis of the bond α (1 → 6), liberating the galactose, which justice to the loss of efficiency throughout the process. An understanding of this mechanism should allow for the development of more mechanically resistant polymers and the increase of drag reduction capacity over time.

Bio-oils of pine wood and sugarcane bagasse were obtained in different conditions of thermal and catalytic pyrolysis. They were analyzed by hydrogen nuclear magnetic resonance (1H NMR), comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC × GC-TOFMS), and negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI(−)-FT-ICR MS) to provide a complementary and comprehensive characterization of the bio-oils. The elucidation of bio-oils composition is essential to assign the best application of bio-oils and the type of process required for upgrading methods. In general, the results obtained by 1H NMR and GC × GC-TOFMS showed a decrease of oxygen compounds (especially acids) and an increase of aromatic compounds when catalytic pyrolysis was used. The compound classes identified in each sample by GC × GC-TOFMS were acids, ketones, cyclic ketones, phenols, O-heterocyclic, and aromatic hydrocarbons. ESI(−)-FT-ICR MS provides relative signals and the bio-oil compounds containing hydroxyl or carboxylic acid groups, such as carboxylic acids and phenols, are selectively ionized. Via ESI(−)-FT-ICR MS, the oxygen-containing compounds determined in bio-oil samples were from O2–O12 classes, with the O4 being the major class. ESI(−)-FT-ICR MS results suggest that use of the ZSM-5 catalyst provides a decrease in the class abundance of higher oxygen atom number (>O5 classes), and consequently, the increase of lower oxygen atom number classes (O2–O4). The integrated results from these three high-resolution techniques were important to comprehensively assess the molecular composition of bio-oils. The 1H NMR provided the whole bio-oils composition profile assessment; GC × GC-TOFMS and ESI(−)-FT-ICR MS results allowed a detailed speciation of the chemical composition of bio-oils.

The selection of the sample preparation method is one of the most critical steps in the determination of metals using atomic spectrometry techniques. The aim of this paper was to propose the use of a novel strategy for crude oil sample preparation, based on the extraction induced by emulsion breaking, prior to the determination of Ba, Ca, Mg and Na by inductively coupled plasma optical emission spectrometry (ICP OES). The emulsions were prepared by mixing the crude oils samples diluted in xylene with 5% m/v Triton X-100 solution in 10% v/v HNO3. The emulsion breaking was performed by heating at 80 ± 2 °C following by centrifugation to improve the separation, resulting in two distinct phases. The aqueous phase was analysed by ICP OES using inorganic standards solutions for external calibration. Ba, Ca, Mg and Na were totally extracted at a single extraction step. The limits of detection were 0.12, 1.2, 0.14 and 5.8 μg L− 1 for Ba, Ca, Mg and Na, respectively. The percentage recoveries ranged from 99 to 104% and the good agreement with the values of the certified reference material (NIST 1634c), when student-t test was applied at 95% confidence limit (p < 0.05), warranted the accuracy of the procedure.

Naphthenic acids are recognized as the main corrosive species in acidic crude oils, although they represent less than 3 wt%. Alternative methods have been developed in an attempt to remove naphthenic acids from the oil, however, their implementation in petrochemical industry still represents a challenge. Herein, a sub-product of the steel industry, steel slag, is evaluated as an economic alternative catalyst and environmentally feasible to remove naphthenic acids present in crude oils. A high-acidity crude oil (TAN = 4.79 mg KOH g−1 and S = 1.022 wt%) was submitted to thermo-catalytic process at 300 and 350 °C during 2, 4 and 6 h and its degradation products were monitored by negative-ion electrospray ionization (ESI) Fourier transform ion cyclotron mass spectrometry (FT-ICR MS), total acid number (TAN) and total sulfur. The main crystalline phases detected by X-ray diffractometry in the catalyst were calcite (CaCO3), silica (SiO2) and magnesia (MgO). Among them, the MgO contributes effectively to promote the thermo-catalytic decarboxylation of naphthenic acid species, with a TAN reduction of 43.50% (4.79 → 1.89 mg KOH g−1) from the original oil to the degraded oil obtained after treatment at 350 °C for 4 h. Acid species with lower pKa values were selectively removed with the ESI(−)FT-ICR MS data confirming an increase in the DBE values from 1–5 to 5–18 for O2 class. Therefore, the catalyst selectively promoted the removal of naphthenic acids via (i) neutralization reaction; (ii) cracking reaction and (iii) MgCO3 formation from CO2 molecules produced by a previous thermal decarboxylation reaction.

Of the salts present in crude oil, sodium, calcium, magnesium, strontium and iron chlorides are the most abundant and are considered the main cause of corrosion in crude oil refineries. Therefore, the objective of this study was to quantify the main chloride counterions (Na, Ca, Mg, Sr and Fe) using inductively coupled plasma-optical emission spectrometry (ICP-OES) after hot solvent extraction (modified ASTM D 6470-99). The procedure developed in this work allowed samples with different °API values (17.4–30.2) originating from the post-salt to be studied. Under the operational conditions of ICP-OES, robust plasma (Mg II/Mg I > 10 for the axial and radial configurations) was obtained based on evaluation of the ratio of the Mg II/Mg I intensities. Furthermore, yttrium was used as an internal standard, resulting in as little interference with the analytical signal as possible. This procedure achieved detection limits on the order of 0.99 mg L−1, 0.025 mg L−1, 0.33 μg L−1, 0.06 ng L−1 and 0.26 μg L−1 for Na, Ca, Mg, Sr and Fe, respectively. The accuracy of the procedure was confirmed through addition/recovery tests (91–120%) and through comparison with the results obtained with flame atomic absorption spectrometry (FAAS). The modified standard test method of ASTM D 6470-99 extraction was compared with microwave-assisted acid digestion and was found to achieve extractions higher than 92.44% for Na and 81.06% for Sr from two of the analysed extracts. Finally, the chloride concentrations obtained via potentiometric titration and ICP-OES (through the analysis of chloride with its counterions) in the aqueous extract indicated a high correlation between Na, Ca, Mg, Sr and Fe and chloride (105.10%, 99.33% and 102.12% for the evaluated samples).

In this work, the corrosion process of AISI 1020 in crude oil, to which different amounts of sea water (0.5 and 4.0% v/v), naphthenic acid (500 and 3000 ppm), and H 2 S (50 and 1000 ppm) were added, was investigated using electrochemical noise at open circuit potential. The different oil samples were prepared using a 2 3 factorial design involving the three species described above. To analyze the obtained data, wavelet transform and energy distribution plot were used. Using this technique it was possible to separate the contributions of two types of corrosion, generalized and localized, in oil samples with different compositions and to analyze the effect of those variables on the changes that occurred during 55 days of immersion in the experiment. The results showed an increase in pitting formation in those steel samples studied in oil containing H 2 S at 50 ppm and 4.0% sea water. The contribution of generalized corrosion on the metallic surface is higher in oil containing 3000 ppm naphthenic acid than in the other experimental conditions. The results were confirmed by morphological analysis of the corroded samples.

Naphthenic acids were identified as the main corrosive species in acidic crudes, although they represent less than 3% wt. The determination of naphthenic acid concentration in oils is one of the first tasks for naphthenic corrosion studies, being expressed still by the total acid number (TAN). However, the TAN is not directly correlated to the corrosivity of naphthenic acids, and therefore it is important to study the naphthenic composition and the corrosion associated with TAN values. Herein, the corrosion process was evaluated on an AISI 316 steel surface immersed in two crude oil samples (G and J) with distinct TAN values (0.33 and 3.10 mg KOH g −1 ) by optical microscopy, atomic force microscopy (AFM) and Raman spectroscopy during a total period of 36 days. For light microscopy images, the naphthenic corrosion is evidenced only on the AISI 316 steel surface from 21 days of exposure to sample J. On the other hand, AFM measurements predicted the “real stage” of naphthenic corrosion, evidenced by topographic and phase images from 21 days for crude oil G and 14 days for sample J. Raman spectra also corroborated AFM data, wherein three corrosion products were identified: goethite (α-Fe(OOH), magnetite (Fe 3 O 4 ), and hematite (Fe 2 O 3 ). The correlation between the naphthenic corrosion and the TAN values was evaluated from negative ion mode electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry data that showed a wider range of DBE distribution (from 1 to 17) and higher naphthenic acid species concentration for the crude oil with higher corrosion power.

Competitive adaptive reweighted sampling-partial least squares (CARS-PLS) and negative-ion mode electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI(-) FT-ICR MS) data were adopted to assess the total acid number (TAN) of crude oil distillation cuts. Two crude oil samples and 24 derivatives with TAN ranging from 0.20 to 0.39 mg of KOH g-1 were investigated. The multivariate calibration PLS model was built with 18 calibration samples and tested with 8 validation samples. CARS-PLS reduced the number of variables from 1610 to only 4, allowing the identification of molecular formulas that are truly related to the TAN. The root mean square error of prediction (RMSEP) obtained was 0.01 mg of KOH g-1, which is lower than the error when using all variables (0.03 mg of KOH g-1). Finally, it was observed that the N and O2 compound classes are the most important classes for providing a better correlation between ESI(-) FT-ICR mass spectra and TAN values.

The oleaginous composition and alcohol used in transesterification have substantial impact on biodiesel properties. This study involves palm oil and its crystallization fractions, olein and stearin oils, with methyl, ethyl, isopropyl and benzyl alcohols, as we seek to investigate the influence of the alcohol on the cold properties, thermal stability, density and viscosity of the resulting biofuel. The products were characterized by GC and 1H NMR spectroscopy. Biofuels produced from the olein oil fraction have superior cold properties compared to those synthesized from palm oil and the palm stearin oil fraction; these properties are attributable to the higher unsaturated contents, which cause the isopropyl biodiesel from palm to exhibit a higher cold filter plugging point (0.3 °C). The use of benzyl alcohol yields a biofuel with high thermal stability but also high viscosity and density values that do not adhere to any international specifications for biodiesel.

Although the term “naphthenic acids” was originally used to describe acids that contain naphthenic rings, today this term is used in a more general sense and refers to all components in the acid extractable fraction. In crude oil, naphthenic acids exist as a complex mixture of compounds with broad polydispersity with respect to both molecular weight and structure. There has been increasing interest in the naphthenic acids in crude oil because of the corrosion problems that cause during oil refining. Herein, two powerful analytical tools, negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry, ESI(-)FT-ICR MS and atomic force microscopy (AFM), were combined to monitor the thermal degradation of naphthenic acids and their corrosion effects on AISI 1020 steel, respectively. Two different acidic crude oils (TAN = 2.38 and 4.79 mg KOH g −1 , and total sulfur = 0.7993 and 1.0220 wt%) have been submitted to thermal treatment at 280, 300 and 350 °C during 2, 4 and 6 h, and characterized by ESI(-)-FT-ICR MS, total acid number (TAN), and total sulfur. The AISI 1020 steel was analyzed by scanning electron microscopy (SEM) and AFM. Generally, heating the crude oil at 350 °C in a period of 6 h, it was observed that a high efficiency (≅80%) and selectivity of thermal decarboxylation process was monitored by decay of TAN (4.79 → 0.44 mg KOH g −1 ). ESI(-)-FT-ICR MS results showed that naphthenic acid species remained after the heating have DBE ranging 1–12 and carbon number from C 15 to C 45 . AFM topographic profile evidenced that the naphthenic acid corrosion of the crude oil with TAN of 4.73 mg KOH g −1 on AISI 1020 steel was profoundly altered and a marked reduction in peak to peak height values (obtained by subtracting the value of the lowest peak by the highest peak in the topographic area examined). Optical images and microphotographs confirmed the presence of irregularities, characterizing the corrosion mechanism as pitting type. The naphthenic corrosion was also evidenced in samples with low TAN value (0.44 mg KOH g −1 ).

The petroleum industry has the interest to know the physicochemical properties of the crude oil before its exploration in order to estimate its costs with processing, transportation, storage and refining. The profile of the recovered oil is determined by the analysis of some physicochemical properties, which may require a long time or a large volume of the sample, delaying decision-making on production and refining. Spectroscopic techniques allow the acquisition of a large amount of information about the sample at a molecular level, in a short time, and with a small amount of sample. This paper aims to identify petroleum profiles using a spectroscopy technique in the middle infrared region associated with methods of standards recognition PCA and kNN. We used 81 oils, divided into two groups: 69 samples of the training set (model construction) and 12 samples of the test set (model performance verification). For all samples, MIR spectra were acquired and measurements of 13 physicochemical properties were obtained. The results show that the methodology using MIR spectroscopy with chemometrics makes it possible to obtain equivalent conclusions about the most similar crude oils, that is, with similar behaviors, when we analyze a database with 13 physicochemical properties of the crude oils.

In this work, API gravity, kinematic viscosity and water content were determined in petroleum oil using Fourier transform infrared spectroscopy with attenuated total reflectance (FT-IR/ATR). Support vector regression (SVR) was used as the non-linear multivariate calibration procedure and partial least squares regression (PLS) as the linear procedure. In SVR models, the multiplication of the spectra matrix by support vectors resulted in information about the importance of the original variables. The most important variables in PLS models were attained by regression coefficients. For API gravity and kinematic viscosity these variables correspond to vibrations around 2900 cm −1 , 1450 cm −1 and below to 720 cm −1 and for water content, between 3200 and 3650 cm −1 , around 1650 cm -1 and below to 900 cm −1 . The SVR model produced a root mean square error of prediction (RMSEP) of 0.25 for API gravity, 22 mm 2 s −1 for kinematic viscosity and 0.26% v/v for water content. For PLS models, the RMSEP values for API gravity was 0.38 mm 2 s −1 , for kinematic viscosity was 27 mm 2 s −1 and for water content was 0.34%. Using the F -test at 95% of confidence it was concluded that the SVR model produced better results than PLS for API gravity determination. For kinematic viscosity and water content the two methods were equivalent. However, a non-linear behavior in the PLS kinematic viscosity model was observed.

In this work, electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI(±)-FT-ICR MS) was applied in the chemical characterization of polar compounds. These compounds were identified as the oxygen-containing compound classes (naphthenic acids, O2 class, and phenols, O1 class), the sulfur-containing compound classes (mainly sulfides, S1 class), and the basic and non-basic nitrogen-containing compound classes (carbazoles and pyridines, N class). For access the sulfur-containing compounds were employed the methylation reactions. As the increasing of distillation cut temperature, the amount of O2 compounds increased (from 9 for cut 2 to 66 for cut 12), and the average molecular weight distribution, Mw, shifted to higher m/z values (Mw = 169 → 321 Da). These results were consistent with the increase of TAN with the boiling point. Plots of the DBE versus the carbon number for the O2 class of heavy distillation cuts (cuts 4–12) suggested a maximum abundance of the carbon numbers located at C12–C18 with a constant DBE of 3. For the nitrogen-containing compounds, 100 compounds were detected with m/z ranging from 160 to 414. Similar to O2 class, the amount of nitrogen species increased, and the Mw shifted for high values in function of distillation cut temperature: 6 species and Mw = 206 Da for cut 3; and 64 species and Mw = 340 Da for cut 12. The structures and the connectivity of naphthenic acids, phenols and pyridines were confirmed using ESI(±)-MS/MS. The most abundant sulfur compounds in heavy distillation cuts presented a carbon number of C23 (for cut 11) and C25 (for cut 12) with constant DBE of 3. Results of ESI(±)-FT-ICR MS contributed to the understanding of the chemical composition of Brazilian crude oil and the establishment of a correlation with the corrosion process.

To choose among the variety of oleaginous plants for biodiesel production, the oil content of several matrices was determined through different low-field 1H nuclear magnetic resonance (NMR) experiments with varied pulse sequences, namely single-pulse, spin-echo, CPMG, and CWFP. The experiments that involved the first three sequences showed high correlation with each other and with the solvent extraction method. The quality of the vegetable oils was also evaluated on the basis of the existing correlation between the T2 values of the oils and their properties, such as viscosity, iodine index, and cetane index. These analyses were performed using HCA and PCA chemometric tools. The results were sufficiently significant to allow separation of the oleaginous matrices according to their quality. Thus, the low-field 1H NMR technique was confirmed as an important tool to aid in the selection of oleaginous matrices for biodiesel production.

In general, esterification reactions are favored by the increase in reaction temperature, excess of one of the reactants (usually alcohol), and additions of acid or basis catalysts. Esterification of oleic acid with methanol catalyzed by Nb2O5·nH2O calcined at different temperatures showed good conversion rates, especially at reaction temperature of 100°C and higher catalyst proportions. PLS calibration showed good results for predicting the amounts of methyl oleate in reaction products.

In this study, 23 biodiesel samples were produced, 20 from used cooking oil and the remaining 3 from refined soybean oil. The following properties were determined in all of the samples (oil and its respective biodiesel): density; viscosity; total acid number and ASTM color. The results indicated high correlation (R > 0.6) between ASTM color of used cooking oil and total acid number of its resultant biodiesel. This high correlation allows prediction of the quality of the biodiesel produced using a simple and fast procedure such as ASTM color.

The chemical and physical properties of a Brazilian heavy oil submitted to plasma treatment were investigated by 1H low- and high-field nuclear magnetic resonance (NMR) combined to the characterization of rheological properties, thermogravimetry and measurement of basic sediments and water (BSW) content. The crude oil was treated in a dielectric barrier discharge plasma reactor, using natural gas, CO2 or H2 as working gas. The results indicated a large drop in the water content of the plasma-treated samples as compared to the crude oil, giving rise to a reduction in the viscosity. No significant chemical change was produced in the oil portion itself, as observed by 1H NMR. The water contents determined by 1H low-field NMR analyses agreed well with those obtained by BSW, indicating the low-field NMR methods as a useful tool for following the effects of plasma treatments on heavy oils, allowing the separation of the effects caused on the water and oil fractions.

The measurement of electrochemical impedance spectroscopy used in situ is a suitable technique for the characterization of oil and water-in-oil emulsions. Nyquist diagrams for dehydrated oils are characterized by the formation of one semi-circle. The equivalent circuit proposed for the dehydrated oil is a resistance and capacitor (ROCO) in parallel. The resistance and conductivity of the oil calculated by impedance were 2.96 Gohm and 486 nS m−1, respectively. Nyquist diagrams for the system composed of water emulsions in oil are mainly characterized by two semi-circles with different relaxation for oil and water-in-oil emulsions. The equivalent circuit is formed by RO and CPEO in parallel and in series with the arrangement of RW/O and CPEW/O in parallel, where RO and CPEO represents the oil, and RW/O and CPEW/O represents water-in-oil emulsions. The resistance of oil (RO) and water-in-oil (RW/O) emulsions increase with the increasing amount of water in the preparation. The increase in resistance shows that the emulsions become more stable with the addition of water. This result is consistent with the formation of rigid films on water–oil interfaces. The impedance measurements were applied to the analysis of the demulsification of the water-in-oil emulsions under an electrostatic field.

The quantity of salts in the crude oils depends on the origin and of the wells production and these salts cause several problems during the transport and the process of refine as corrosions, incrustations and deactivation of the employed catalysts in the refineries. In this study were implemented changes for improvements in the execution of ASTM D 6470 method and has also developed a new methodology of extraction system of salts using process of mechanical agitation without heating. The results of the optimization produce larger efficiency and safety to the process compared to the traditional ASTM method.

Direct esterification on naphthoquinone presented itself as a hard task. Usual methodologies apply acyl chloride in pyridine or anhydrides but with long-chain esters this procedure proved to be ineffective because of the low yields obtained. We present a new synthesis of long-chain esters of juglone based on Steglich esterification using a cheap Lewis acid as cocatalyst. Yields obtained are considerably better than those found previously. Computational chemistry was used to evaluate the effects of CeCl3 as cocatalyst. Prepared compounds were tested as wax deposition inhibitors in crude oil. Palmitic ester of juglone was able to lower 4 ºC on the wax appearance temperature (WAT) of the studied oil, representing a reduction of precipitated normal paraffin of 1.5% m/m. A esterificação direta de naftoquinonas mostrou-se uma tarefa difícil. Metodologias mais comuns envolvem a aplicação de cloretos de acila em piridina ou anidridos, entretanto, quando ácidos de cadeia longa são utilizados tais metodologias se mostram ineficientes devido aos baixos rendimentos obtidos. Apresentamos uma nova síntese de ésteres de cadeia longa de juglona baseado na esterificação de Steglich utilizando um ácido de Lewis barato como cocatalisador. Rendimentos obtidos são consideravelmente maiores do que os reportados previamente. Química computacional foi utilizada para avaliar os efeitos do CeCl3 como cocatalisador. Os compostos preparados foram testados como inibidores de deposição de parafinas em petróleo. Éster palmítico da juglona foi capaz de reduzir 4 ºC na temperatura de início de aparecimento de cristais (WAT) do óleo estudado, representando uma redução de 1,5% m/m de parafinas normais precipitadas.

The purpose of this study was to evaluate the best operating conditions of ICP OES for the determination of Na, Ca, Mg, Sr and Fe in aqueous extract of crude oil obtained after hot extraction with organic solvents (ASTM D 6470-99 modified). Thus, the full factorial design and central composite design were used to optimize the best conditions for the flow of nebulization gas, the flow of auxiliary gas, and radio frequency power. After optimization of variables, a study to obtain correct classification of the 18 samples of aqueous extract of crude oils (E1 to E18) from three production and refining fields was carried out. Exploratory analysis of these extracts was performed by principal component analysis (PCA), hierarchical cluster analysis (HCA) and linear discriminant analysis (LDA), using the original variables as the concentration of the metals Na, Ca, Mg, Sr and Fe determined by ICP OES.

O mercado brasileiro de embalagens empregado ao armazenamento de petróleo e seus derivados vem crescendo a cada ano, sendo constituídas basicamente por polietileno de alta densidade (PEAD) e polipropileno (PP). Contudo durante o armazenamento, a matriz polimérica fica exposta ao óleo, comprometendo suas propriedades físicas e consequentemente a durabilidade do material. Portanto, estudos relacionados com a interação entre solventes orgânicos e a matriz polimérica tornam-se importantes. Neste trabalho, a interação do PEAD e PP com diferentes solventes apolares (tolueno, n-heptano, n-decano e n-tetradecano) foram estudadas em função da temperatura (25, 50 e 80 ºC). Os valores de ganho de massa, coeficientes de difusão, sorção, permeabilidade e parâmetros de mecanismo de transporte foram calculados. O ganho de massa observado para o PP foi maior do que para o PEAD, em todas as temperaturas, sendo que o tolueno foi o solvente responsável pelo maior ganho de massa, atingindo o equilíbrio em um menor intervalo de tempo. Esse resultado corrobora com os valores de coeficiente de difusão e de permeabilidade, que aumentaram na seguinte ordem: n-heptano > n-decano > n-tetradecano. Uma ordem inversa foi observada para os solventes alifáticos quando os valores de coeficiente de sorção foram calculados. O mecanismo de transporte foi também estudado através da regressão dos dados de sorção, sendo classificado como anômalo. Recently, the brazilian packing market of polymeric materials applied to storage of petroleum and its devired is growing every year, being basically constituted from two polymers: high density polyethylene (HDPE) and polypropylene (PP). However, during the storage process, the polymeric matrix can interact with the oil, thus compromising, its physical-chemical properties and durability. Therefore, it is necessary to study the migration mechanism existent between organic solvents and polymeric materials. In this work, the interaction of HDPE and PP with different organic solvents (toluene, n-heptane, n-decane and n-tetradecane) was studied as function of temperature (25, 50 and 80 ºC). Values of weight gain, coefficients of diffusion, sorption and permeability and mechanism of transport were calculated. The values of weight gain for PP were higher than PEAD in all temperatures studied. Among the solvents used, the toluene had the highest weight gain, reaching consequently, an equilibrium plateau in a lower time period. This result is good agreement with the diffusion and permeability coefficients, which the values increased in the following order: toluene > n-heptane > n-decane > n-tetradecane. An appositive behavior was observed for aliphatic solvents when the sorption coefficient values were analyzed. The mechanism of transport phenomenon was also studied, being classified as anomalous transport.

According to the relevant literature, the Diels-Alder reaction of furan without a catalyst can last several weeks and shows a low yield due to the diene's low reactivity. The use of Lewis acid catalysts or high pressures is described as an effective method for improving the reaction yields. This paper describes our recent study on the use of niobium pentachloride as the catalyst in Diels-Alder reactions between furan and several reactive dienophiles, among which methyl acrylate showed good yields, especially at lower temperatures. Other dienophiles have shown lower yields because of problems such as byproduct formation and the high reversibility of the reaction.

Neste trabalho foi desenvolvida uma nova metodologia de reciclagem química do poli(tereftalato de etileno) grau garrafa pós-consumo, PETpc, através da reação de despolimerização em meio alcalino (solução de hidróxido de sódio, NaOH, de 7,5 mol L-1 a 100 ºC) e como catalisador o tensoativo catiônico brometo de hexadeciltrimetrilamônio, CTAB (1 × 10-2 mol L-1). A presença de CTAB aumentou o rendimento da reação em cerca de 85% e reduziu o tempo reacional de 6 para 2 h, quando utilizado em mistura NaOH/CTAB na proporção de 4:1 (% v/v) com 2 g de PETpc. O produto final, o monômero ácido tereftálico, TPA, foi caracterizado por análise termogravimétrica, calorimetria diferencial varredura, espectroscopia na região do infravermelho com transformada de Fourier e espectrometria de massas. Os resultados foram comparados com os da matéria-prima, PETpc. Além disso, o catalisador CTAB permaneceu no meio reacional (fase aquosa), sem interferir no processo de purificação do TPA. In this work, a new analytical methodology has been developed for the chemical recycling of post-consumption bottle-grade poly(ethylene terephthalate), PETpc through depolymerization reaction in alkaline solution (NaOH solution of 7.5 mol L-1 at 100 ºC), using the surfactant cetyl trimethyl ammonium bromide (CTAB, 1 × 10-2 mol L-1) as catalyst. The presence of CTAB increased the reaction performance by ca. 85%, while the reaction time was decreased from 6 to 2 h when the mixture NaOH/CTAB was used in a proportion of 4:1 (% v/v) with 2 g of PETpc. The final product, the monomer terephthalic acid (TPA), was characterized by thermogravimetry analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy and mass spectrometry. The results were compared with those for the raw material, PETpc. Furthermore, the catalyst CTAB remained in the alkaline environment (aqueous phase), without interfering with the TPA purification process.

O potencial da técnica de espectroscopia de infravermelho com transformada de Fourier e acessório de reflexão total atenuada (FTIR-ATR) foi avaliado para o monitoramento da degradação da poliamida 11 (PA-11) usada em dutos flexíveis. As amostras foram submetidas a envelhecimento em reatores com pressão controlada e atmosfera inerte. Os corpos de prova foram imersos em água deionizada (pH 7), nas temperaturas de 110, 120 e 140 ºC por um período de até 50 dias. A técnica recomendada para monitoramento da degradação da PA-11 é a viscosimetria, através de medidas da viscosidade inerente corrigida (VIC) e a análise termogravimétrica (TGA). O comportamento observado para a VIC e TGA durante o envelhecimento possibilitou a construção de modelos que correlacionam com a técnica de FTIR-ATR. A partir dos resultados de FTIR-ATR, a variação na intensidade da banda atribuída à fase amorfa, 1161 cm-1, possibilitou o monitoramento do envelhecimento quando associamos a técnica a modelos quimiométricos como o de regressão dos mínimos quadrados parciais, PLS. Portanto, a técnica FTIR-ATR pode ser uma nova alternativa no monitoramento da degradação hidrolítica da PA-11, eliminando assim o uso de solventes orgânicos tóxicos e reduzindo, consequentemente, o tempo de análise. The potential of the infrared spectroscopy with the attenuated total reflection technique (FTIR-ATR) was evaluated to monitor degradation of polyamide 11, PA-11, applied in flexible pipes. The samples were subjected to aging on reactors with controlled pressure and atmosphere. The samples were immersed in deionized water, pH 7, at temperatures of 110, 120 and 140 ºC over a period of up to 50 days. The typical technique recommended for monitoring PA-11 degradation is viscometry from inherent viscosity corrected (VIC) and thermogravimetric (TGA) measurements. TGA and VIC results allowed the use of chemometric models that can be related to FTIR-ATR spectra, with assignment of a band to the amorphous phase (1161 cm-1) of PA-11. The chemometric model generated from PLS data was satisfactory in predicting the aging of PA-11. Therefore, FTIR-ATR can be used as a new analytical methodology to monitor PA-11 degradation, thus eliminating the use of toxic organic solvents and reducing the time required for the analysis.

In the present study three pre-treatment procedures were developed and compared following Cr determination by GF AAS: sample dilution with toluene, emulsion formation and direct sampling of crude oil. The limits of detection for the developed procedures were 1.9 ng g-1 for sample dilution with toluene, 2.8 ng g-1 for emulsion formation and 0.73 ng g-1 for direct sampling. The accuracy of the three procedures was assessed by analysis of NIST1085b and recovery tests. High recoveries and good agreement between found and certified values were obtained in all cases. However, results indicate that sample dilution with toluene is not recommended for samples below 15ºAPI. The other two procedures showed the same performance for the samples with different API degrees (8 to 38), but the direct sampling showed better sensitivity besides minimizing the chances of analyte losses or contamination. No presente estudo, três procedimentos de pré-tratamento e determinação de Cr por GF AAS foram desenvolvidos e comparados: diluição da amostra com tolueno, formação de emulsão e amostragem direta do petróleo. Os limites de detecção para os procedimentos desenvolvidos foram 1,9 ng g-1 para a diluição da amostra com tolueno, 2,8 ng g-1 para a formação de emulsão e 0,73 ng g-1 para a amostragem direta. A exatidão dos três procedimentos foi avaliada analisando-se o material NIST1085b e por testes de recuperação. Em todos os procedimentos foram obtidos altos valores de recuperação e boa concordância entre os teores determinados e os teores certificados. No entanto, os resultados indicam que a diluição da amostra com tolueno não é recomendada para amostras com grau API abaixo de 15. Os outros dois procedimentos mostraram o mesmo desempenho para as amostras com diferentes graus API (8-38), mas a amostragem direta apresentou melhor sensibilidade além de minimizar as chances de perdas do analito ou contaminação.

Antimony is a common catalyst in the synthesis of polyethylene terephthalate used for food-grade bottles manufacturing. However, antimony residues in final products are transferred to juices, soft drinks or water. The literature reports mentions of toxicity associated to antimony. In this work, a green, fast and direct method to quantify antimony, sulfur, iron and copper, in PET bottles by X-ray fluorescence spectrometry is presented. 2.4 to 11 mg Sb kg-1 were found in 20 samples analyzed. The coupling of the multielemental technique to chemometric treatment provided also the possibility to classify PET samples between bottle-grade PET/recycled PET blends by Fe content.