Food additives are chemical substances added to improve organoleptic characteristics, in this context, there are several synthetic dyes, such as sunset yellow, tartrazine, erioglaucine, allura red, indigo carmine, and new coccine, that can also be identified through different analytical techniques such as infrared spectroscopy, UV-Vis spectrophotometry, high performance liquid chromatography with diode array detector and mass spectrometry. Therefore, the objective of this work was to compare methods developed for different analytical techniques, in order to identify the one that presents greater efficiency in certain applications. For this, the patterns of the dyes were analyzed, as well as their mixtures and foods that had them. As a result, the CLAE-DAD presents excellent selectivity and linearity of the calibration curves, but it presents higher LD and LQ values when compared to the UV-Vis, in turn the infrared provides information regarding functional groups and bonds. Mass spectrometry showed great capabilities in identifying the molecular formula and better selectivity in the absence of the erioglaucine dye. It is not feasible to indicate the best or worst analytical approach, but it is possible to point out which one is more suitable for each application. Regarding the quantification capacity, chromatography and UV-Vis are good alternatives, but in mixtures containing more than one dye, CLAE-DAD is more suitable due to the better selectivity. Regarding the identification capacity, mass spectrometry, especially FT-ICR MS, is the most appropriate technique to propose molecular formulas due to its high resolution and mass accuracy. The advantage of FTIR was the easier sample preparation, being able to analyze the dyes in the solid state.

Beer is commonly produced with four inputs: water, malt, hops, yeast and, in some cases, brewing adjuncts. Industrial and artisanal processes essentially follow the same steps and may undergo minor changes due to the style of beer. Despite this, many consumers attribute higher quality to craft beer compared to industrial ones. In this study, we applied the analytical techniques of infrared (IR), hydrogen nuclear magnetic resonance (1H NMR) and mass spectrometry (ESI(±)FT-ICR MS) to discriminate craft beers from industrial ones (brands common to the Brazilian market). In addition, Partial Least Squares (PLS) and Support Vector Machine (SVR) regression were used to estimate some beer properties (pH, total acidity (meq·L-1, color (EBC), bitterness (IBU), alcohol content (%v/v) and density (g·mL-1)). The use of the IR allowed the identification of vibrations attributed to chemical compounds common to beverages, such as water (3320 and 1640 cm-1), carbohydrates (1500 cm-1) and ethanol (1050-1040 and 875-865 cm-1). 1H NMR showed good applicability in identifying classes of organic compounds in the beverage, where signs attributed to alcohols, organic acids, carbohydrates and amino acids were observed. The ESI(+)FT-ICR MS allowed the identification of chemical compounds present in beverages, allowing the construction of a fingerprint of the beers. In addition, the application of chemometric tools enabled the prediction of physicochemical properties, presenting promising results in the prediction of alcohol content (RMSEC 0.2430 and RMSEP 0.3929) and bitterness (RMSEC 1.3022 and RMSEP 1.6008), and also in the classification regarding the manufacturing process (craft and industrial beer).

The correlation between iron distribution in octahedral or tetrahedral sites in synthetic magnetite and zinc spinel ferrites and their catalytic properties were investigated in this work. The zinc-doped nanomagnetites were prepared by co-precipitation method and annealed at 420 °C. X-ray diffraction, UV-Vis, X-ray absorption and 57Fe Mössbauer spectroscopies were used to identify iron sites. The obtained results showed that ZnII replaces the relatively smaller FeIII cation in the tetrahedral sites, increasing the cubic lattice dimension, and this replacement remarkably enhances the catalytic effectiveness of the Zn-spinel ferrite towards the indigo carmine degradation compared to undoped magnetite. The indigo carmine degradation experiments were carried out using photo-Fenton method in which 50 mL of indigo carmine dye aqueous solutions (20 mg L−1, pH 3.0), 20 mg ZnxFe(3-x)O4, and 2.0 mL H2O2 (aqueous solution at 0.028 mol L−1) were placed under UV light at 25 °C. Under these experimental conditions the degradation rate of indigo carmine was superior to 98%.

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.

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.

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.

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.

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.

De acordo com a literatura, a reação de Diels-Alder de furano sem uso de catalisador pode durar várias semanas e apresenta baixo rendimento devido à baixa reatividade do dieno. O uso de catalisadores ácidos de Lewis ou de altas pressões são descritos como métodos eficazes para melhorar o rendimento da reação. Este trabalho descreve nosso estudo recente sobre a utilização de pentacloreto de nióbio, como catalisador em reações de Diels-Alder entre furano e alguns dienófilos reativos, entre os quais o acrilato de metila apresentou bons rendimentos, especialmente sob temperaturas mais baixas. Outros dienófilos apresentaram rendimentos mais baixos devido a problemas, tais como a formação de produtos secundários e de elevado caráter de reversibilidade da reação.

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.

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.

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.

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.

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.

Utiliza-se o método coordenada geradora Hartree-Fock para gerar bases Gaussianas adaptadas para os átomos de Li (Z=3) até Xe (Z=54). Neste método, integram-se as equações de Griffin-Hill-Wheeler-Hartree-Fock através da técnica de discretização integral. Comparam-se as funções de ondas geradas neste trabalho com as funções de ondas Roothaan-Hartree-Fock de Clementi e Roetti (1974) e com outros conjuntos de bases relatados na literatura. Para os átomos estudados aqui, os erros em nossas energias totais relativos aos limites numéricos Hartree-Fock são sempre menores que 7,426 milihartree.

The generator coordinate Hartree-Fock method is used to generate adapted Gaussian basis sets for the atoms from Li (Z=3) through Xe (Z=54). In this method the Griffin-Hill-Wheeler-Hartree-Fock equations are integrated through the integral discretization technique. The wave functions generated in this work are compared with the widely used Roothaan-Hartree-Fock wave functions of Clementi and Roetti (1974), and with other basis sets reported in the literature. For all atoms studied, the errors in our total energy values relatively to the numerical Hartree-Fock limits are always less than 7.426 mhartree.