Discrimination between similar woods by molecular fluorescence and partial least squares

Wood is an extremely complex biological material, which can show macroscopic similarities that make it difficult to discriminate between species. Discrimination between similar wood species can be achieved by either anatomic or instrumental methods, such as near infrared spectroscopy (NIR). Although different spectroscopy methods are currently available, few studies have applied them to discriminate between wood species. In this study, we applied a partial least squares-discriminant analysis (PLS-DA) model to evaluate the viability of using direct fluorescence measurements for discriminating between Eucalyptus grandis, Eucalyptus urograndis, and Cedrela odorata. The results show that molecular fluorescence is an efficient technique for discriminating between these visually similar wood species. With respect to calibration and the validation samples, we observed no misclassifications or outliers

Characterization of wood decay by rot fungi using colorimetry and infrared spectroscopy

Amostras de madeiras de marupá (Simarouba amara) e andiroba (Carapa guianenis) foram submetidas ao ataque dos fungos Trametes versicolor (podridão branca) e Gloeophylum trabeum (podridão parda). A colorimetria foi empregada para determinar as cores das madeiras antes e após o ataque dos fungos. Para acompanhar a variação do teor dos compostos químicos foi utilizada a técnica de espectroscopia de refletância difusa no infravermelho médio. Ambas as espécies foram consideradas não resistentes ao fungo de podridão branca. Para o fungo de podridão parda, a andiroba foi considerada resistente e o marupá não resistente. Ambas as espécies de madeira se apresentaram mais escuras após o ataque do fungo Gloeophyllum trabeum. Já o ataque do fungo Trametes versicolor causou clareamento na madeira da andiroba e escureceu ligeiramente o marupá. Os resultados da análise dos espectros de infravermelho mostraram que em ambas as espécies de madeira houve redução na intensidade das bandas de celulose, hemiceluloses e lignina após o ataque do Trametes versicolor, e redução somente na intensidade da banda de celulose após o ataque do Gloeophyllum trabeum.Wood samples of marupá (Simarouba amara) and andiroba (Carapa guianenis) were submitted to Trametes versicolor (white rot) and Gloeophylum trabeum (brown rot) fungi attack. Colorimetry was used to determine the color of the wood before and after wood decaying fungi. To evaluate the changes in chemical compounds levels in the wood samples, the diffuse reflectance medium infrared spectroscopy was used. Both wood were non resistant against white rot fungus, while with brown rot attack andiroba was resistant and marupá was not. After Gloeophyllum trabeum attack both woods changed to a darken color, and after Trametes versicolor attack andiroba changed to a lighter color and marupá darkened slightly, The analysis showed a reduction in the peak intensity of cellulose, hemicellulose and lignin, for both species, after Trametes versicolor attack and a reduction in the peak intensity of cellulose after Gloeophyllum trabeum attack

Detection of counterfeit Durateston using Fourier transform infrared spectroscopy and partial least squares : discriminant analysis

Medicines containing anabolic steroids are one of the main targets for counterfeiting worldwide, including Brazil. The aim of this work was to propose a method for discriminating original and counterfeit Durateston® ampoules by Fourier transform infrared spectroscopy (FTIR) followed by chemometric analysis. Ninety-six ampoules of Durateston®, 49 originals and 47 counterfeits, were analyzed by gas chromatography with mass spectrometry (GC-MS) and by FTIR. Principal component analysis was applied to the infrared spectra to detected different clusters, corresponding to original samples and different types of counterfeits. A partial least squares - discriminant analysis method was proposed to discriminate original samples from those counterfeits that were indistinguishable from the originals in the infrared analysis. A training subset comprised of one-third of the available spectra was used to establish a suitable model that correctly discriminated all samples in the test subset, resulting in 0% of false positive or negative results and 100% of efficiency rate, sensitivity and specificity. In addition to the low cost of the infrared technique, the proposed method is fast, reliable and suitable to replace GC-MS methods used in Durateston® ampoule analyses to detect counterfeiting

Brazilian Federal District cocaine chemical profiling : mass balance approach and new adulterant routinely quantified (Aminopyrine)

From a set of 159 samples seized by Brazilian Federal police between 2010 to 2013 in the Federal District, the major component chemical profiling routine analyses revealed the presence of cocaine with purity range of 5.5 to 99.9% (mean 69.8%). Most cocaine base samples show moderately and not oxidized levels, whereas cocaine hydrochloride samples exhibit moderate to high oxidation degrees. More than 40% of the analyzed samples did not have any adulterant. Phenacetin was the most abundant adulterant (24% average purity). Aminopyrine, a new adulterant, was identified and quantified only in cocaine base samples, mainly as a trace adulterant but also as a major compound. In most samples adulterated with aminopyrine, phenacetin was also identified as a major adulterant, suggesting a possible association of the two pharmaceuticals in the cutting process. Aminopyrine was not detected in 2010 seizures, but became a common adulterant throughout the years of 2011 to 2013. A mass balance approach analysis also established that adulterants are responsible for only 12% of the mass of all seizures (i.e., 84 kg), whereas 77% (i.e., 553 kg) is due to alkaloids (cocaine and cis/trans-cinnamoylcocaine), contributing to provide forensic intelligence information to police investigators

Characterization of wood decay by rot fungi using colorimetry and infrared spectroscopy

Amostras de madeiras de marup\ue1 ( Simarouba amara ) e andiroba ( Carapa guianenis ) foram submetidas ao ataque dos fungos Trametes versicolor (podrid\ue3o branca) e Gloeophylum trabeum (podrid\ue3o parda). A colorimetria foi empregada para determinar as cores das madeiras antes e ap\uf3s o ataque dos fungos. Para acompanhar a varia\ue7\ue3o do teor dos compostos qu\uedmicos foi utilizada a t\ue9cnica de espectroscopia de reflet\ue2ncia difusa no infravermelho m\ue9dio. Ambas as esp\ue9cies foram consideradas n\ue3o resistentes ao fungo de podrid\ue3o branca. Para o fungo de podrid\ue3o parda, a andiroba foi considerada resistente e o marup\ue1 n\ue3o resistente. Ambas as esp\ue9cies de madeira se apresentaram mais escuras ap\uf3s o ataque do fungo Gloeophyllum trabeum. J\ue1 o ataque do fungo Trametes versicolor causou clareamento na madeira da andiroba e escureceu ligeiramente o marup\ue1. Os resultados da an\ue1lise dos espectros de infravermelho mostraram que em ambas as esp\ue9cies de madeira houve redu\ue7\ue3o na intensidade das bandas de celulose, hemiceluloses e lignina ap\uf3s o ataque do Trametes versicolor, e redu\ue7\ue3o somente na intensidade da banda de celulose ap\uf3s o ataque do Gloeophyllum trabeum.Wood samples of marup\ue1 ( Simarouba amara ) and andiroba ( Carapa guianenis ) were submitted to Trametes versicolor (white rot) and Gloeophylum trabeum (brown rot) fungi attack. Colorimetry was used to determine the color of the wood before and after wood decaying fungi. To evaluate the changes in chemical compounds levels in the wood samples, the diffuse reflectance medium infrared spectroscopy was used. Both wood were non resistant against white rot fungus, while with brown rot attack andiroba was resistant and marup\ue1 was not. After Gloeophyllum trabeum attack both woods changed to a darken color, and after Trametes versicolor attack andiroba changed to a lighter color and marup\ue1 darkened slightly, The analysis showed a reduction in the peak intensity of cellulose, hemicellulose and lignin, for both species, after Trametes versicolor attack and a reduction in the peak intensity of cellulose after Gloeophyllum trabeum attack

Evaluation of a NIR handheld device and PLS-DA for discrimination of six similar amazonian wood species

Supervising wood exploitation can be very challenging due to the existence of many similar species and the reduced number of wood identification experts to meet the demand. There is evidence that valuable endangered wood species are being smuggled disguised as other species. Near infrared spectroscopy (NIRS) and chemometrics has been successfully used to discriminate between Amazonian wood species using high resolution instruments. In this study, a handheld spectrometer was evaluated for the discrimination of six visually similar tropical wood species using PLS-DA. Woods of mahogany (Swietenia macrophylla) and cedar (Cedrela odorata), both high value tropical timber species included in Appendixes II and III of the CITES, respectively; crabwood (Carapa guianensis); cedrinho (Erisma uncinatum); curupixá (Micropholis melinoniana); and jatobá (Hymenea coubaril). The data for model development and validation take into account both laboratory and field measurements. Outlier exclusion was performed based on Hotelling T2, residuals Q and errors in the estimated class values. The efficiency rates were higher than 90% for all species, showing that the handheld NIR combined with PLS-DA succeeded in discriminate between these species. These results stimulate the application of handheld NIR spectrometers in the supervision of wood exploitation, which can contribute to the species preservation

Exploratory analysis of the distribution of lignin and cellulose in woods by raman imaging and chemometrics

The determinations of cellulose and lignin are important in wood analysis from both perspectives: chemistry composition, commercial and industrial application of woods. In this context, Raman image spectroscopy was applied in the determination of cellulose and lignin distribution in wood surfaces of Swietenia macrophylla King (Mahogany) and Eucalyptus hybrid (E. urophylla × E. camaldulensis). The relative concentration maps were obtained by applying a multivariate curve resolution procedure. The estimated Raman spectra for cellulose and lignin agrees with the ones available in the literature. The cellulose concentration maps showed similar variations for both studied species with an average value of nearly 85% as obtained by the reference method. The lignin concentration maps were somewhat different. The Eucalyptus hybrid presents a broader distribution (20 to 45%) while for Mahogany it is nearly constant, around 25%, with localized regions presenting contents of 45 to 65% of lignin. The reference method showed that the mean lignin content of both species is 27%. The cellulose and lignin concentration maps agree with the biological functions of the anatomic structures observed in the images

Application and validation of second order calibration models in analytical chemistry

Orientador: Ronei Jesus PoppiTese (doutorado) - Universidade Estadual de Campinas, Instituto de QuimicaResumo: Modelos de calibração de segunda ordem vêm sendo cada vez mais aplicados, principalmente pela possibilidade de determinar analitos mesmo na presença de interferentes da amostra. Contudo, a validação desses modelos ainda não é possível por dificuldades na determinação de algumas figuras de mérito. Esta tese teve como objetivos estudar a determinação e avaliar a consistência de algumas figuras de mérito em modelos de calibração de segunda ordem, desenvolver programas que facilitem sua determinação. Também foram comparardos a eficiência dos modelos de quadrados mínimos bilinear (BLLS) e quadrados mínimos parciais desdobrado (UPLS), ambos utilizando o processo de bilinearização residual (RBL), com os modelos de análise de fatores paralelos (PARAFAC) e resolução multivariada de curvas (MCR). Foram desenvolvidos quatro estudos, abordando as determinações de: (1) hidrocarbonetos policíclicos aromáticos, (2) riboflavina e piridoxina em matrizes lácteas (ambos por emissão e excitação de fluorescência), (3) ácido acetilsalicílico e ascórbico em fármacos por análise por injeção em fluxo com gradiente de pH e (4) pesticidas e metabólitos em vinho por cromatografia líquida de alta eficiência. Os resultados demonstraram que as figuras de mérito apresentam boa consistência, sendo observada influência de interferentes na sensibilidade, seletividade e nos erros obtidos. Contudo, observou-se a necessidade de desenvolvimentos nas estimativas de incerteza e seletividade, onde duas novas propostas para o modelo UPLS são descritas. Os modelos comparados foram equivalentes na maior parte dos casos, sendo que a escolha correta do número de fatores no RBL requer um conjunto de amostras externasAbstract: Second order calibration models are becoming widely applied in analytical chemistry, mainly due to the possibility to determine analytes even in the presence of interferences. However, an appropriate validation of these models is not possible due to the difficult in the determination of some figures of merit. The aims of this thesis were to study and evaluate the determination of some figures of merit of the most applied second order calibration models, to develop softwares to perform its determination easier and to compare the performance of the bilinear least squares (BLLS) and the unfold partial least squares (UPLS), both applying the residual bilinearization process (RBL), with the models parallel factor analysis (PARAFAC) and multivariate curve resolution (MCR). Four applications were developed, which study the determination of: (1) polycyclic aromatic hydrocarbons, (2) riboflavin and pyridoxine in dairy supplements (both using excitation and emission fluorescence), (3) acetylsalicylic and ascorbic acids in pharmaceutical samples by FIA and pH gradient and (4) pesticides and metabolites in wine samples by HPLC. The results show that the estimated figures of merit present a good agreement with their expected values, also been observed the effects of the interferences of the sample in the sensitivity, selectivity and uncertainty values. It was also observed the necessity of new developments in the estimates of selectivity and uncertainty parameters, where two new approaches for the model UPLS are described. The compared models were equivalents in most of the situations and it was observed that the choice of the correct number of factors in the RBL requires the use of an independent data setDoutoradoQuimica AnaliticaDoutor em Ciência