Aplicação e avanços da espectroscopia de luminescência em análises farmacêuticas

This paper provides a review on the latest advances and applications of the luminescence spectroscopy for the development of pharmaceuticals analyses methods, basically based on the photo- and chemiluminescence. The different forms of the drugs determination on pharmaceuticals through the fluorescence and chemiluminescence are discussed. The analyses include the drugs native fluorescence (liquid and solid-phases); the fluorescence from the oxidizing or reducing forms of the drug; the fluorescence from the chemical derivatization and their photochemistry and hydrolysis reactions. The quenching of luminescence and chemiluminescence generation for the pharmaceutical quantification are also shown. Finally, the trends and future perspectives of the luminescence spectroscopy in the field of the pharmaceutical research are discussed.

Construção de um espectrógrafo de projeção e sua utilização em demonstrações de espectroscopia óptica

This article describes a projection spectrograph for use in optical spectroscopy classrooms demonstrations. The apparatus is based on an overhead projector and permits the visualization of several phenomena such as, light dispersion by diffraction gratings, diffraction order, optical fluorescence, continuous and discrete optical emission spectra, and light absorption by liquids and solids. A historical survey about the optical spectroscopy development is also presented.

Determination of ambroxol in syrups using diffuse reflectance spectroscopy

This paper reports an analytical method for the determination of ambroxol in micellar medium by spot test-diffuse reflectance spectroscopy. The reflectance measurements were performed analyzing the colored compound (λ= 520 nm) produced from the reaction between ambroxol and p-dimethylaminocinnamaldehyde on the surface filter paper. The linear range was from 1.21 × 10"3 to 9.65 × 10"3 mol L-1 (500 - 4000 μg mL-1). The limit of detection and quantification were 3.50 x 10-4 mol L-1 (145 μg mL-1) and 1.16 x 10-3 mol L-1 (481 μg mL-1), respectively. Five commercial samples were analysed and the results obtained by the proposed method were in good agreement with those obtained by the literature method at 95% confidence level.

Characterization of the major nutritional components of Caryocar brasiliense fruit pulp by nmr spectroscopy

Pequi (Caryocar brasiliense Camb.), a typical fruit of Brazilian Cerrado, is well known in regional cookery and used in folk medicine to treat various illnesses. Mass spectrometry and chromatographic methods have identified the organic composition of pequi fruit pulp; however, NMR spectroscopy is used for the first time to characterize the nutritional components of organic and aqueous-ethanolic extracts. This spectroscopic technique determined the triacylglycerols in the pequi organic fraction, which is constituted mainly by oleate and palmitate esters, and detected the carbohydrate mixtures as the major components of aqueous and ethanolic fractions, respectively. In this study, presence of phenolic compounds was only evidenced in the ethanolic fraction.

Obtaining high purity silica from rice hulls

Many routes for extracting silica from rice hulls are based on direct calcining. These methods, though, often produce silica contaminated with inorganic impurities. This work presents the study of a strategy for obtaining silica from rice hulls with a purity level adequate for applications in electronics. The technique is based on two leaching steps, using respectively aqua regia and Piranha solutions, which extract the organic matrix and inorganic impurities. The material was characterized by Fourier-transform infrared spectroscopy (FTIR), powder x-ray diffraction (XRD), x-ray fluorescence (XRF), scanning electron microscopy (SEM), particle size analysis by laser diffraction (LPSA) and thermal analysis.

Adsorption of glyphosate in a forest soil: a study using Mössbauer and FT-IR spectroscopy

We studied the adsorption of glyphosate (GPS) onto soil mineral particles, using FT-IR and Mössbauer spectroscopy. From IR measurements for samples collected under native vegetation of a forest reserve, bands at 1632 and 1407 cm-1 could be attributed to the interaction between the carboxylic group of GPS and structural Al3+ and Fe3+ on the surface of mineral particles; bands at 1075 and 1000 cm-1 were observed only for cultivated soil. Mössbauer spectra for these soils were definitely fitted using a broad central doublet in addition to the magnetic component. This multiple quadrupolar component may be attributed to all non-magnetic Fe3+ contributions, including that of the GPS/Fe3+ complex.

Discrimination of native wood charcoal by infrared spectroscopy

Brazil is one of the largest producers and consumers of charcoal in the world. About 50% of its charcoal comes from native forests, with a large part coming from unsustainable operations. The anatomic identification of charcoal is subjective; an instrumental technique would facilitate the monitoring of forests. This study aimed to verify the feasibility of using medium and near infrared reflectance spectroscopy to discriminate native (ipê) from plantation charcoals (eucalyptus). Principal Components Analysis, followed by Discriminant Factorial Analysis formed two different groups indicated by Mahalanobis distances of 40.6 and 80.3 for near and mid infrared, respectively. Validation of the model showed 100% efficacy.

Synchronous scanning phosphorimetry for the selective determination of chrysene: a metrological study

Room-temperature phosphorimetry was used to quantify trace levels of chrysene in sugar-cane spirits and in fish bile. A selective phosphorescence enhancer (AgNO3) and synchronous scanning allowed the detection of ng amounts of chrysene. Accuracy (113 ± 17%) and selectivity was evaluated using the CRM-NIST-1647d - Priority Pollutant Polycyclic Aromatic Hydrocarbons in acetonitrile. Analysis of sugar-cane spirit samples enabled recovery of 108 ± 18% which agreed with the one achieved using HPLC. Method's uncertainty was equivalent to 3.4 ng of the analyte, however, the analyte pre-concentration (SPE) improved sensibility and minimized the relative uncertainty. Characterization and homogeneity studies in fish bile were also performed.

Pigmentos de pinturas rupestres pré-históricas do sítio Letreiro do Quinto, Pedro II, Piauí, Brasil

The Letreiro do Quinto rock shelter is located in the rural area of the city of Pedro II, Piauí, Brazil. The sandstone walls of the shelter are covered with prehistoric rupestrian paintings, painted in patterns of yellow and light and dark red hues. The chemical-mineralogical characterization of the prehistoric pigments was made with energy dispersive spectroscopy, scanning electron microscopy, energy dispersive X-ray fluorescence and 57Fe transmission Mössbauer spectroscopy at 110 K. Results confirm the occurrence of hematite- and goethite-rich ochres and also that the pigment layers are indeed made of a mixture of clay minerals mixed with iron oxides.

Characterization of the antibiotic doripenem using physicochemical methods: chromatography, spectrophotometry, spectroscopy and thermal analysis

Doripenem was characterized through physicochemical and spectroscopic techniques, as well as thermal analysis. TLC (Rf = 0.62) and HPLC (rt = 7.4 min) were found to be adequate to identify the drug. UV and infrared spectra showed similar profile between doripenem bulk and standard. The ¹H and 13C NMR analysis revealed chemical shifts that allowed identifying the drug. Thermal analysis demonstrated three steps with mass loss, at 128, 178 and 276 ºC. The work was successfully applied to qualitative analysis of doripenem, showing the reported methods can be used for physicochemical characterization of doripenem

A fluorescence-based assay for octreotide in kinetic release from depot formulations

Here we report the validation of a derivatization method that makes use of fluorescamine as a selective reactant for the quantitative analysis of peptide and protein drugs in the dissolution profile from depot formulations. Typical current methods require separation of the nano/microparticles and time-consuming chromatographic runs. In this study we report a method which can be conducted without the need for complete physical separation of the particles or removal of the unreacted probe. This method was used here for the analysis of the release profile of octreotide in a depot formulation, with results in excellent agreement with reported chromatographic assays.

Separation and characterization of asphaltenic subfractions

The structure of the various asphaltenic subfractions found in crude oil was evaluated. For this purpose, C5 asphaltenes were extracted from an asphaltic residue using n-pentane as the flocculant solvent. The different subfractions were isolated from the C5 asphaltenes by the difference in solubility in different solvents. These were characterized by infrared spectroscopy, nuclear magnetic resonance, X-ray fluorescence, elementary analysis and mass spectrometry. The results confirmed that the subfractions extracted with higher alkanes had greater aromaticity and molar mass. However, small solubility variations between the subfractions were attributed mainly to the variation in the concentrations of cyclical hydrocarbon compounds and metals.

Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy and chemometric techniques for the determination of adulteration in petrodiesel/biodiesel blends

We propose an analytical method based on fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy to detect the adulteration of petrodiesel and petrodiesel/palm biodiesel blends with African crude palm oil. The infrared spectral fingerprints from the sample analysis were used to perform principal components analysis (PCA) and to construct a prediction model using partial least squares (PLS) regression. The PCA results separated the samples into three groups, allowing identification of those subjected to adulteration with palm oil. The obtained model shows a good predictive capacity for determining the concentration of palm oil in petrodiesel/biodiesel blends. Advantages of the proposed method include cost-effectiveness and speed; it is also environmentally friendly.

Grape juice quality control by means of ¹H nmr spectroscopy and chemometric analyses

This work shows the application of ¹H NMR spectroscopy and chemometrics for quality control of grape juice. A wide range of quality assurance parameters were assessed by single ¹H NMR experiments acquired directly from juice. The investigation revealed that conditions and time of storage should be revised and indicated on all labels. The sterilization process of homemade grape juices was efficient, making it possible to store them for long periods without additives. Furthermore, chemometric analysis classified the best commercial grape juices to be similar to homemade grape juices, indicating that this approach can be used to determine the authenticity after adulteration.

Application of fourier transform infrared spectroscopy, chemical and chemometrics analyses to the characterization of agro-industrial waste

Agroindustrial waste in general presents significant levels of nutrients and organic matter and has therefore been frequently put to agricultural use. In this context, the objective of this study was to determine the chemical composition, nitrogen, phosphorus, potassium, calcium, magnesium and carbon content, as well as the qualitative characteristics through Fourier transform infrared spectroscopy of four samples of poultry litter and one sample of cattle manure, from the southwestern region of Paraná, Brazil. Results revealed that, in general, the poultry litter presented higher amount of nutrients and carbon than the cattle manure. The infrared spectra allowed identification of the functional groups present and the differences in degree of sample humification. The statistical treatment confirmed the quantitative and qualitative differences revealed.