In this study, biopolymer-based pH-sensitive hydrogels have been successfully prepared using alginate, κ-carrageenan and pectin aimed at the encapsulation of pancreatin (hydrolytic enzymes like α-amylase, lipase and protease) so as to preserve enzymatic activities. Hydrogels have been characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), swelling degree and swelling profile. Encapsulation efficiency and in vitro studies on delayed release have also been evaluated. All hydrogels presented low swelling degree and enzyme release in a gastric medium. On the other hand, high swelling degree and enzyme release were observed in an intestinal medium. Alginate hydrogel achieved optimal results concerning encapsulation efficiency (18, 68 and 53% for α-amylase, lipase and protease, respectively) and delayed release (363, 7,673 and 17,497 U for α-amylase, lipase and protease, respectively) which has been afterwards compared to a commercial pancreatin formulation (CreonTM 10,000). Thus, it presented better performance than its commercial formulation, mainly in respect of lipase.

Abstract The present study investigated the encapsulation of β-galactosidase in carrageenan, pectin and its hybrid hydrogels by using the ionotropic gelation method. The material obtained was characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG/DTG) and scanning electron microscopy (SEM). The effects of pH, temperature and storage time were evaluated in terms of the catalytic activity of the free and encapsulated enzyme. Addition studies were conducted evaluating the performance of catalytic activity in vitro conditions. Carrageenan, pectin and hybrid hydrogels presented encapsulation efficiency of 58 ± 1%, 72 ± 1% and 77 ± 2%, respectively. The pectin hydrogel showed the higher β-galactosidase activity in pH and temperature tests. However, the carrageenan hydrogel exhibited best stability after been stored for three months. Carrageenan and pectin hydrogels were 2.0 and 2.4 times more efficiently than commercial tablet in the releasing β-galactosidase under in vitro conditions, respectively. The results suggest that pectin and carrageenan hydrogels may be useful for the development of new formulation of β-galactosidase.

Abstract Fosamprenavir calcium is an amprenavir prodrug of the protease inhibitors class used in the treatment of patients with acquired immunodeficiency syndrome (AIDS). Different solid forms of this drug are described in patents, in this sense studies on the physico-chemical characterization and stability are relevant for the selection of a solid form with adequate features for pharmaceutical purposes. In the present work form I (commercial) and amorphous of fosamprenavir calcium were characterized by the techniques of Differential Scanning Calorimetry (DSC), Thermogravimetry (TGA), Powder X-ray Diffraction (PXRD), Fourier-Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Furthermore, the chemical and polymorphic stability of the commercial form were evaluated by DSC, PXRD, FTIR and High-Performance Liquid Chromatography (HPLC). In the studies of characterization, thermal analyses allied to spectroscopic methods (PXRD and FTIR) demonstrated that the presence of water in the crystalline structure of Form I is fundamental for maintaining its crystallinity. In studies of accelerated stability the techniques of DSC, PXRD and FTIR showed that Form I does not suffer phase change when submitted to controlled conditions of temperature and humidity. Moreover, HPLC and FTIR proved the chemical stability of this solid form of fosamprenavir, thus demonstrating its suitability for pharmaceutical purposes.

The present study reports the synthesis and characterization of complexes formed among humic (HA) and fulvic acids (FA) derived from poultry wastes and ions Cu2+, Fe2+ and Zn2+. The release of such metals in a buffer solution simulating the soil solution was also evaluated. After complexation, the Fourier transform infrared (FTIR) spectra presented alterations in the absorption bands related to changes in the humic structure, thus indicating the complexation with phenolic and carboxylic groups. Thermogravimetric analyses demonstrated that complexed metals decreased the thermal stability of humic substances. Analyses by atomic absorption spectroscopy (AAS) demonstrated that the release of metals is directly related to the origin of the sample, type of interaction of metal and humic structure and conditions of the medium in which the complex is inserted.

Roasted and ground coffee is targeted by fraudulent addiction of products. In this way the determination of contaminants in coffee has economic and nutritional importance. In this study, the coffee adulteration by corn were detected using DSC (differential scanning calorimetry) and FTIR (Fourier transform infrared spectroscopy) coupled to PCA (principal component analysis), and PLS (partial least squares) models. Three different levels of roasted and ground Coffea arabica L. were used to prepare mixtures with roasted and ground corn. The level of adulteration used was between 0.5 to 40% (m/m). It was observed that both DSC and FTIR coupled with PCA are able to discriminate adulterated from unadulterated samples of coffee by corn at levels below 1%. PLS models were built with DSC and FTIR data reaching good correlation between the values of estimated and reference concentrations, with RMSECV (root mean square error of cross-validation) lower than 3.5% for DSC data and 2.7% for FTIR data.

O processo de eletrooxidação da 1,2-benzopirona (BP) foi avaliado através de medidas de voltametria linear e espectroscopia de impedância eletroquímica sobre o eletrodo de carbono vítreo em tampão fosfato dibásico de potássio. O número de elétrons envolvidos na eletrooxidação é um e o produto formado é uma cetona. O produto da oxidação fica adsorvido na superfície do eletrodo formando um filme, o qual bloqueia os sítios ativos e a espessura do filme aumenta após medidas consecutivas. As condições de analise foram otimizadas usando planejamento fatorial e matriz Doehlert. A metodologia eletroquímica foi comparada com a cromatografia líquida de alta eficiência (HPLC) com um limite de detecção para a BP de 26,4 µmol L-1. Os resultados voltamétricos foram estatisticamente semelhantes aos obtidos por HPLC, mas o método proposto é mais rápido, simples, de fácil aquisição e de alta sensibilidade, e não exige grandes quantidades de solventes orgânicos.

The electrooxidation of 1,2-benzopyrone (BP) was assessed via linear voltammetry and electrochemical impedance spectroscopy on a glassy carbon electrode in dibasic potassium phosphate buffer. The oxidation process for BP requires one electron and forms a ketone. This oxidation product was adsorbed by the electrode surface to form a film that blocks active sites and increases in thickness over consecutive measurements. The oxidation conditions were optimized using factorial design and Doehlert matrices. This electrochemical method was compared to high performance liquid chromatography (HPLC), which has a detection limit of 26.4 µmol L-1 for BP. The voltammetric results were statistically similar to those from HPLC; however, the method was faster, simpler, more easily acquired, more sensitive, and required less organic solvent.

Diffuse reflectance near-infrared (DR-NIR) spectroscopy associated with partial least squares (PLS) multivariate calibration is proposed for a direct, non-destructive, determination of total nitrogen in wheat leaves. The procedure was developed for an Analytical Instrumental Analysis course, carried out at the Institute of Chemistry of the State University of Campinas. The DR-NIR results are in good agreement with those obtained by the Kjeldhal standard procedure, with a relative error of less than ± 3% and the method may be used for teaching purposes as well as for routine analysis.

Process Analytical Chemistry (PAC) is an important and growing area in analytical chemistry, that has received little attention in academic centers devoted to the gathering of knowledge and to optimization of chemical processes. PAC is an area devoted to optimization and knowledge acquisition of chemical processes, to reducing costs and wastes and to making an important contribution to sustainable development. The main aim of this review is to present to the Brazilian community the development and state of the art of PAC, discussing concepts, analytical techniques currently employed in the industry and some applications.

Foi estabelecido um método cromatográfico rápido e simples para a determinação de riboflavina em leite bovino, na presença de tetraciclinas. Para tanto, as proteínas foram precipitadas com ácido tricloroacético e a separação realizada por CLAE em fase reversa com detector de fluorescência. Foi utilizada uma coluna C8 com eluição isocrática e fase móvel acetato de sódio 0,1 mol L-1, cloreto de cálcio 35 mmol L-1, EDTA 25 mmol L-1: metanol (65:35 v/v). O método foi validado mediante avaliação dos seguintes parâmetros: linearidade (0,9980), faixa linear (0,50 a 1,30 µg mL-1), precisão intra e inter-ensaio (RSD < 0,5%), exatidão (recuperação 92%) e limites de detecção e de quantificação (0,75 µg mL-1 e 0,22 µg mL-1, respectivamente). O método foi aplicado na análise de leite integral e desnatado, mostrando-se robusto na presença de substâncias fluorescentes como as tetraciclinas, e quando comparado com o método espectrofluorimétrico, não revelou diferença significativa (p < 0,05) entre os resultados obtidos.

An easy and simple chromatographic method for the determination of riboflavin in bovine milk in the presence of tetracyclines was established. For this, the proteins were precipitated with trichloroacetic acid and the separation was carried out by reversed-phase HPLC with fluorescence detection. A C8 column was used with isocratic flow using a mobile phase consisting of 0.1 mol L-1 sodium acetate, 35 mmol L-1calcium chloride and 25 mmol L-1 EDTA : methanol (65:35 v/v). The method was validated by means of the following parameters: linearity (0.9980), linear range (0.50 - 1.30 µg mL-1), intra- and inter-assay precision (RSD < 0.5%), accuracy (recovery 92%), and detection and quantitation limits (0.75 µg mL-1 and 0.22 µg mL-1, respectively). The method was applied for analysis of full cream and skimmed milk, showing robustness in the presence of tetracyclines, and when compared with a spectrofluorimetric method showed no significant difference (p < 0.05) between the results obtained.

Since the last decade, the combined use of chemometrics and molecular spectroscopic techniques has become a new alternative for direct drug determination, without the need of physical separation. Among the new methodologies developed, the application of PARAFAC in the decomposition of spectrofluorimetric data should be highlighted. The first objective of this article is to describe the theoretical basis of PARAFAC. For this purpose, a discussion about the order of chemometric methods used in multivariate calibration and the development of multi-dimensional methods is presented first. The other objective of this article is to divulge for the Brazilian chemical community the potential of the combination PARAFAC/spectrofluorimetry for the determination of drugs in complex biological matrices. For this purpose, two applications aiming at determining, respectively, doxorrubicine and salicylate in human plasma are presented.