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.

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

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.

Dielectric spectroscopy and thermally stimulated discharge current in PEEK film

The complex permittivity of films of polyether ether ketone (PEEK) has been investigated over a wide range of frequency. There is no relaxation peak in the range of 1Hz to 10(5) Hz but in the low-frequency side (10-4 Hz) there is an evidence of a peak that also can be observed by thermally stimulated discharge current measurements. That peak is related with the glass transition temperature (Tg) of the polymer. The activation energy of the relaxation was found to be 0.44 eV, similar to that of several synthetic polymers. Space charges are important in the conduction mechanism as shown by discharging transient.

Lychnophoric acid from Lychnophora pinaster: a complete and unequivocal assignment by NMR spectroscopy

The investigation of the hexane extract from aerial parts of Lychnophora pinaster provided, besides others substances, the E-isomer of lychnophoric acid, a sesquiterpene derivative previously isolated from L. affinis.

Determination of hydrochlorothiazide in pharmaceutical formulations by diffuse reflectance spectroscopy

This paper describes a method for quantitative spot test analysis of hydrochlorothiazide using diffuse reflectance spectroscopy. The reflectance measurements were performed analyzing the colored compound (l = 585 nm) produced from the reaction between hydrochlorothiazide and p-dimethylaminocinnamaldehyde (PDAC) in acid medium. This reaction occurred on filter paper after heating to 80ºC for 8 minutes. Factorial designs allowed varying multiple reaction factors simultaneously in order to obtain the best reaction conditions. These factors included heating temperature, heating time, acid volume and PDAC volume. The linearity was studied in the range of 3.36x10-2 to 1.01x10-1 mol L-1 with a correlation coefficient of 0.998. The limit of detection was estimated to be 1.32x10² mol L-1. Commercial samples were analyzed using the proposed method and the results were favorably compared with those of the United States Pharmacopeia method, showing that quantitative spot test analysis by diffuse reflectance could be successfully used to determine hydrochlorothiazide in medicines.

Determination of atenolol in pharmaceutical formulations by diffuse reflectance spectroscopy

A simple analytical method for quantification of atenolol in pharmaceutical formulations by diffuse reflectance spectroscopy is described. The method is based on the reaction, on the filter paper surface, between the drug and p-chloranil producing a colored compound. The best reaction conditions were obtained with 20 µL of atenolol solution and 20 µL of p-chloranil. All reflectance measurements were carried out at 550 nm and the linear range was from 1.13x10-2 to 7.88x10-2 mol L-1 (r = 0.9992). The limit of detection was 2.80 x 10-3 mol L-1. The proposed method was successfully applied to analysis of different commercial brands of pharmaceutical formulations and the results obtained by the proposed method were in good agreement with those obtained using the British Pharmacopoeia method.

White mold detection in common beans through leaf reflectance spectroscopy

ABSTRACT This study aimed to identify wavelengths based on leaf reflectance (400-1050 nm) to estimate white mold severity in common beans at different seasons. Two experiments were carried out, one during fall and another in winter. Partial Least Squares (PLS) regression was used to establish a set of wavelengths that better estimates the disease severity at a specific date. Therefore, observations were previously divided in two sub-groups. The first one (calibration) was used for model building and the second subgroup for model testing. Error measurements and correlation between measured and predicted values of disease severity index were employed to provide the best wavelengths in both seasons. The average indexes of each experiment were of 5.8% and 7.4%, which is considered low. Spectral bands ranged between blue and green, green and red, and red and infrared, being most sensitive for disease estimation. Beyond the transition ranges, other spectral regions also presented wavelengths with potential to determine the disease severity, such as red, green, and near infrared.

Bioelectrical impedance spectroscopy for the assessment of body fluid volumes of term neonates

The assessment of fluid volume in neonates by a noninvasive, inexpensive, and fast method can contribute significantly to increase the quality of neonatal care. The objective of the present study was to calibrate an acquisition system and software to estimate the bioelectrical impedance parameters obtained by a method of bioelectrical impedance spectroscopy based on step response and to develop specific equations for the neonatal population to determine body fluid compartments. Bioelectric impedance measurements were performed by a laboratory homemade instrument. The volumes were estimated in a clinical study on 30 full-term neonates at four different times during the first month of life. During the first 24 hours of life the total body water, extracellular water and intracellular water were 2.09 ± 0.25, 1.20 ± 0.19, and 0.90 ± 0.25 liters, respectively. By the 48th hour they were 1.87 ± 0.27, 1.08 ± 0.17, and 0.79 ± 0.21 liters, respectively. On the 10th day they were 2.02 ± 0.25, 1.29 ± 0.21, and 0.72 ± 0.14 liters, respectively, and after 1 month they were 2.34 ± 0.27, 1.62 ± 0.20, and 0.72 ± 0.13 liters, respectively. The behavior of the estimated volume was correlated with neonatal body weight changes, leading to a better interpretation of such changes. In conclusion, this study indicates the feasibility of bioelectrical impedance spectroscopy as a method to help fluid administration in intensive care neonatal units, and also contribute to the development of new equations to estimate neonatal body fluid contents.

Spectroscopic studies on the interaction of efonidipine with bovine serum albumin

Efonidipine hydrochloride is an antihypertensive and antianginal agent with fewer side effects and is better tolerated in the treatment of hypertension with renal impairment. Its interaction with bovine serum albumin (BSA) is of great use for the understanding of the pharmacokinetic and pharmacodynamic mechanisms of the drug. The binding of efonidipine to BSA was investigated by fluorescence spectroscopy and circular dichroism. BSA fluorescence was quenched by efonidipine, due to the fact that efonidipine quenched the fluorescence of tryptophan residues mainly by the collision mode. The thermodynamic parameters ΔH0 and ΔS0 were 68.04 kJ/mol and 319.42 J·mol-1·K-1, respectively, indicating that the hydrophobic interactions played a major role. The results of circular dichroism and synchronous fluorescence measurements showed that the binding of efonidipine to BSA led to a conformational change of BSA. The fraction of occupied sites (θ) for the 8-anilino-1-naphthalein-sulfonic acid (ANS)-BSA system is 85%, whereas for the NZ-105-BSA system, it is 53%, which suggests that the interaction of ANS with BSA is stronger than that of NZ-105 with BSA. Binding studies in the presence of ANS indicated that efonidipine competed with ANS for hydrophobic sites of BSA. The effects of metal ions on the binding constant of the efonidipine-BSA complex were also investigated. The presence of metal ions Zn2+, Mg2+, Al3+, K+, and Ca2+ increased the binding constant of efonidipine_BSA complex, which may prolong the storage period of NZ-105 in blood plasma and enhance its maximum effects.

Proton magnetic resonance spectroscopy of the frontal, cingulate and perirolandic cortices and its relationship to skin conductance in patients with schizophrenia

The aim of the present study was to determine whether specific subgroups of schizophrenic patients, grouped according to electrodermal characteristics, show differences in the N-acetylaspartate/creatine plus choline (NAA / (Cr + Cho)) ratios in the frontal, cingulate and perirolandic cortices. Skin conductance levels (SCL) and skin conductance responses to auditory stimulation were measured in 38 patients with schizophrenia and in the same number of matched healthy volunteers (control). All subjects were submitted to multivoxel proton magnetic resonance spectroscopic imaging. When compared to the control group, patients presented significantly lower NAA / (Cr + Cho) ratios in the right dorsolateral prefrontal cortex (schizophrenia = 0.95 ± 0.03; control = 1.12 ± 0.04) and in the right (schizophrenia = 0.88 ± 0.02; control = 0.94 ± 0.03) and left (schizophrenia = 0.84 ± 0.03; control = 0.94 ± 0.03) cingulates. These ratios did not differ between electrodermally responsive and non-responsive patients. When patients were divided into two groups: lower SCL (less than the mean SCL of the control group minus two standard deviations) and normal SCL (similar to the control group), the subgroup with a lower level of SCL showed a lower NAA / (Cr + Cho) ratio in the left cingulate (0.78 ± 0.05) than the controls (0.95 ± 0.02, P < 0.05) and the subgroup with normal SCL (0.88 ± 0.03, P < 0.05). There was a negative correlation between the NAA / (Cr + Cho) ratio in the left cingulate of patients with schizophrenia and the duration of the disease and years under medication. These data suggest the existence of a schizophrenic subgroup characterized by low SCL that could be a consequence of the lower neuronal viability observed in the left cingulate of these patients.

Thalamic metabolic abnormalities in patients with Huntington's disease measured by magnetic resonance spectroscopy

Huntington's disease (HD) is a neurologic disorder that is not completely understood; its fundamental physiological mechanisms and chemical effects remain somewhat unclear. Among these uncertainties, we can highlight information about the concentrations of brain metabolites, which have been widely discussed. Concentration differences in affected, compared to healthy, individuals could lead to the development of useful tools for evaluating the progression of disease, or to the advance of investigations of different/alternative treatments. The aim of this study was to compare the thalamic concentration of metabolites in HD patients and healthy individuals using magnetic resonance spectroscopy. We used a 2.0-Tesla magnetic field, repetition time of 1500 ms, and echo time of 135 ms. Spectra from 40 adult HD patients and 26 control subjects were compared. Quantitative analysis was performed using the LCModel method. There were statistically significant differences between HD patients and controls in the concentrations ofN-acetylaspartate+N-acetylaspartylglutamate (NAA+NAAG; t-test, P<0.001), and glycerophosphocholine+phosphocholine (GPC+PCh;t-test, P=0.001) relative to creatine+phosphocreatine (Cr+PCr). The NAA+NAAG/Cr+PCr ratio was decreased by 9% and GPC+PCh/Cr+PCr increased by 17% in patients compared with controls. There were no correlations between the concentration ratios and clinical features. Although these results could be caused by T1 and T2 changes, rather than variations in metabolite concentrations given the short repetition time and long echo time values used, our findings point to thalamic dysfunction, corroborating prior evidence.