Evaluation of acid digestion techniques to estimate chromium contents in cattle feces

The objective of this work was to evaluate the accuracy of digestion techniques using nitric and perchloric acid at the ratios of 2:1, 3:1, and 4:1 v v-1, in one- or two-step digestion, to estimate chromium contents in cattle feces, using sodium molybdate as a catalyst. Fecal standards containing known chromium contents (0, 2, 4, 6, 8, and 10 g kg-1) were produced from feces of five animals. The chromium content in cattle feces is accurately estimated using digestion techniques based on nitric and perchloric acids, at a 3:1 v v-1 ratio, in one-step digestion, with sodium molybdate as a catalyst.

Multidetector-row computed tomography in the preoperative diagnosis of intestinal complications caused by clinically unsuspected ingested dietary foreign bodies: a case series emphasizing the use of volume rendering techniques

Objective The present study was aimed at describing a case series where a preoperative diagnosis of intestinal complications secondary to accidentally ingested dietary foreign bodies was made by multidetector-row computed tomography (MDCT), with emphasis on complementary findings yielded by volume rendering techniques (VRT) and curved multiplanar reconstructions (MPR). Materials and Methods The authors retrospectively assessed five patients with surgically confirmed intestinal complications (perforation and /or obstruction) secondary to unsuspected ingested dietary foreign bodies, consecutively assisted in their institution between 2010 and 2012. Demographic, clinical, laboratory and radiological data were analyzed. VRT and curved MPR were subsequently performed. Results Preoperative diagnosis of intestinal complications was originally performed in all cases. In one case the presence of a foreign body was not initially identified as the causal factor, and the use of complementary techniques facilitated its retrospective identification. In all cases these tools allowed a better depiction of the entire foreign bodies on a single image section, contributing to the assessment of their morphology. Conclusion Although the use of complementary techniques has not had a direct impact on diagnostic performance in most cases of this series, they may provide a better depiction of foreign bodies' morphology on a single image section.

Preparación y caracterización de la zeolita MCM-22 y de su precursor laminar

The layered precursor of MCM-22 was prepared with different Si/Al ratios: 15, 25, 50, 100 and ¥. Upon heat treatment these precursors form MCM-22 zeolite. Both layered precursor and MCM-22 zeolite were characterized by several techniques: Chemical Analysis by Atomic Absorption Spectroscopy (AAS), X-Ray Diffraction (XRD), Thermo-gravimetric Analysis (TGA), Pore Analysis by N2 and Ar adsorption, Scanning Electron Microscopy (SEM), Infrared Spectroscopy (IR) and Temperature Programmed Desorption of ammonium (TPD).

Uso de lodo de estação de tratamento de água centrifugado em matriz de concreto de cimento portland para reduzir o impacto ambiental

An alternative application of the humid sludge from the Passaúna WTP, located in Curitiba's metropolitan area, is proposed for concrete structures, partially replacing aggregates and cement. For the investigation, a reference concrete and four concrete mixtures with sludge were produced, and from these, two mixtures, containing 4% and 8% of sludge (m/m), were analyzed by different techniques: X ray fluorescence, X ray diffraction, thermo-gravimetric analysis, physicochemical analysis, compressive strength, etc. The properties were evaluated and the results indicate that the mixtures can be applied in different situations as cast structures for construction of concrete walls. Mixtures with more than 4% of sludge are restricted to applications where the workability of the concrete is not required, such as for residential pavements, sidewalks and stepping floors.

Determination of moisture content and water activity in algae and fish by thermoanalytical techniques

The water content in seafoods is very important since it affects their sensorial quality, microbiological stability, physical characteristics and shelf life. In this study, thermoanalytical techniques were employed to develop a simple and accurate method to determine water content (moisture) by thermogravimetry (TG) and water activity from moisture content values and freezing point depression using differential scanning calorimetry (DSC). The precision of the results suggests that TG is a suitable technique to determine moisture content in biological samples. The average water content values for fish samples of Lutjanus synagris and Ocyurus chrysurus species were 76.4 ± 5.7% and 63.3 ± 3.9%, respectively, while that of Ulva lactuca marine algae species was 76.0 ± 4.4%. The method presented here was also successfully applied to determine water activity in two species of fish and six species of marine algae collected in the Atlantic coastal waters of Bahia, in Brazil. Water activity determined in fish samples ranged from 0.946 - 0.960 and was consistent with values reported in the literature, i.e., 0.9 - 1.0. The water activity values determined in marine algae samples lay within the interval of 0.974 - 0.979.

Simultaneous spectrophotometric determination of ezetimibe and simvastatin in pharmaceutical preparations using chemometric techniques

Two spectrophotometric methods are described for the simultaneous determination of ezetimibe (EZE) and simvastatin (SIM) in pharmaceutical preparations. The obtained data was evaluated by using two different chemometric techniques, Principal Component Regression (PCR) and Partial Least-Squares (PLS-1). In these techniques, the concentration data matrix was prepared by using the mixtures containing these drugs in methanol. The absorbance data matrix corresponding to the concentration data matrix was obtained by the measurements of absorbances in the range of 240 - 300 nm in the intervals with Δλ = 1 nm at 61 wavelengths in their zero order spectra, then, calibration or regression was obtained by using the absorbance data matrix and concentration data matrix for the prediction of the unknown concentrations of EZE and SIM in their mixture. The procedure did not require any separation step. The linear range was found to be 5 - 20 µg mL-1 for EZE and SIM in both methods. The accuracy and precision of the methods were assessed. These methods were successfully applied to a pharmaceutical preparation, tablet; and the results were compared with each other.

Comparison of gas chromatographic and gravimetric methods for quantization of total fat and fatty acids in foodstuffs

Different methods to determine total fat (TF) and fatty acids (FA), including trans fatty acids (TFA), in diverse foodstuffs were evaluated, incorporating gravimetric methods and gas chromatography with flame ionization detector (GC/FID), in accordance with a modified AOAC 996.06 method. Concentrations of TF and FA obtained through these different procedures diverged (p< 0.05) and TFA concentrations varied beyond 20 % of the reference values. The modified AOAC 996.06 method satisfied both accuracy and precision, was fast and employed small amounts of low toxicity solvents. Therefore, the results showed that this methodology is viable to be adopted in Brazil for nutritional labeling purposes.

Determinação da densidade de corrente de corrosão em meios de baixa condutividade: uso de microeletrodos para minimizar a queda ôhmica

The gravimetric and electrochemical tests are the most common techniques used in determining the corrosion rate. However, the use of electrochemical polarization is limited to electrolytes with sufficient conductivity for which Tafel curves are linear. In this study, we investigated a technique in which working microelectrodes of AISI 1020 steel were used to obtain the Tafel curves in diesel oil. The strategy was to reduce the electrode area and hence the ohmic drop. The diameter of the microelectrode was reduced to a value where the compensation of the Tafel curves became unnecessary. The results showed that for electrodes with diameters below 50 μm, the ohmic drop tends to a minimum and independent of the microelectrode diameter.

Comparison of USEPA 3050B and ISO 14869-1: 2001 digestion methods for sediment analysis by using FAAS and ICP-OES quantification techniques

A study of the partial USEPA 3050B and total ISO 14869-1:2001 digestion methods of sediments was performed. USEPA 3050B was recommended as the simpler method with less operational risk. However, the extraction ability of the method should be taken in account for the best environmental interpretation of the results. FAAS was used to quantify metal concentrations in sediment solutions. The alternative use of ICP-OES quantification should be conditioned by a previous detailed investigation and eventual correction of the matrix effect. For the first time, the EID method was employed for the detection and correction of the matrix effect in sediment ICP-OES analysis. Finally, some considerations were made about the level of metal contamination in the area under study.

Authenticity study of Phyllanthus species by NMR and FT-IR Techniques coupled with chemometric methods

The importance of medicinal plants and their use in industrial applications is increasing worldwide, especially in Brazil. Phyllanthus species, popularly known as "quebra-pedras" in Brazil, are used in folk medicine for treating urinary infections and renal calculus. This paper reports an authenticity study, based on herbal drugs from Phyllanthus species, involving commercial and authentic samples using spectroscopic techniques: FT-IR, ¹H HR-MAS NMR and ¹H NMR in solution, combined with chemometric analysis. The spectroscopic techniques evaluated, coupled with chemometric methods, have great potential in the investigation of complex matrices. Furthermore, several metabolites were identified by the NMR techniques.

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.

TREATMENT OF WASTE FROM ATOMIC EMISSION SPECTROMETRIC TECHNIQUES AND REUSE IN UNDERGRADUATE LAB CLASSES FOR QUALITATIVE ANALYSIS

Flame atomic absorption spectrometry (FAAS) and inductively coupled plasma optical emission spectrometry (ICP OES) are widely used in academic institutions and laboratories for quality control to analyze inorganic elements in samples. However, these techniques have been observed to underperform in sample nebulization processes. Most of the samples processed through nebulization system are discarded, producing large volumes of waste. This study reports the treatment and reuse of the waste produced from ICP OES technique in a laboratory of analytical research at the Universidade Federal do Ceará, Brazil. The treatment of the waste was performed by the precipitation of elements using (NH4)2CO3. Subsequently, the supernatant solution can be discarded in accordance with CONAMA 430/2011. The precipitate produced from the treatment of residues can be reused as a potential sample in undergraduate qualitative analytical chemistry lab classes, providing students the opportunity to test a real sample.

Flavonoid extraction from Alpinia zerumbet (Pers.) Burtt et Smith leaves using different techniques and solvents

The current study aims to verify the best method for a rapid and efficient extraction of flavonoids from Alpinia zerumbet. Dried leaves were extracted using distillated water and ethanol 70% by extraction methods of shaking maceration, ultrasonic, microwave and stirring. By the application of TLC and reversed-phase HPLC techniques the rutin and kaempferol-3-O-glucuronide were detected. Ethanol 70% was more efficient for flavonoids extraction than water. No significant yielding variation was verified for ultrasonic, microwave and stirring methods using ethanol 70% (11 to 14%). The relative concentration of rutin and kaempferol-3-O-glucuronide, respectively, was higher by ultrasonic (1.5 and 5.62 mg g-1 dried leaves, respectively) and by microwave (1.0 and 6.64 mg g-1 dried leaves) methods using ethanol. Rapid and simplified extraction proceeding optimize phytochemical work and acquisition of secondary metabolites.

ESTABLISHMENT TECHNIQUES FOR TROPICAL LEGUMES IN THE UNDERSTORY OF A EUCALYPTUS PLANTATION

This study evaluated establishment methods for a mixture of herbaceous forage legumes [Centrosema acutifolium, Clitoria ternatea, Pueraria phaseoloides, Stylosanthes Campo Grande (Stylosanthes capitata + S. macrocephala), Calopogonium mucunoides, Lablab purpureus, Arachis pintoi, and Aeschynomene villosa] under the shade of an Eucalyptus grandis plantation submitted to thinning (40%) 8 years after planting in Anhembi, São Paulo (22°40'S, 48°10'W, altitude of 455 m). The experiment started in December 2008 and consisted of the comparison of the following four types of seed incorporation by light disc harrowing: (1) broadcast sowing without seed incorporation; disc harrowing before (2) or after (3) planting, and (4) disc harrowing before and after planting. Ninety days after planting, the number of legume plants/m2 and the percentage of ground cover by the plants varied between the treatments tested; however, the treatments had no effect on the dry matter accumulation of forage legumes. Disc harrowing before planting yielded superior results compared to the treatments without disc harrowing and disc harrowing after planting. At the end of the experimental period, the plots contained Arachis, Centrosema, Stylosanthes, and Pueraria. The dry matter accumulated by Centrosema corresponded to 73% of total dry matter yield of the plots. The participation of Arachis, Centrosema and Stylosanthes in final dry matter composition of the plots varied according to establishment method. The advantages of the use of species mixtures rather than monocultures in the understory of forest plantations were discussed.

Data mining techniques for identification of spectrally homogeneous areas using NDVI temporal profiles of soybean crop

The aim of this study was to group temporal profiles of 10-day composites NDVI product by similarity, which was obtained by the SPOT Vegetation sensor, for municipalities with high soybean production in the state of Paraná, Brazil, in the 2005/2006 cropping season. Data mining is a valuable tool that allows extracting knowledge from a database, identifying valid, new, potentially useful and understandable patterns. Therefore, it was used the methods for clusters generation by means of the algorithms K-Means, MAXVER and DBSCAN, implemented in the WEKA software package. Clusters were created based on the average temporal profiles of NDVI of the 277 municipalities with high soybean production in the state and the best results were found with the K-Means algorithm, grouping the municipalities into six clusters, considering the period from the beginning of October until the end of March, which is equivalent to the crop vegetative cycle. Half of the generated clusters presented spectro-temporal pattern, a characteristic of soybeans and were mostly under the soybean belt in the state of Paraná, which shows good results that were obtained with the proposed methodology as for identification of homogeneous areas. These results will be useful for the creation of regional soybean "masks" to estimate the planted area for this crop.