Infrared spectroscopy applied to the drugs quality control. Part I: multivariate regression for the quantification of potassium diclofenac

No presente trabalho são combinadas as potencialidades das ferramentas quimiométricas e as facilidades na obtenção de espectros pela técnica de espectroscopia por refletância difusa no infravermelho médio com transformada de Fourier (DRIFTS), visando à dosagem do fármaco diclofenaco de potássio. Foram formuladas 20 diferentes concentrações do princípio ativo em excipiente amido entre 0,15 e 0,50 mg/g, com variação de aproximadamente 0,02 mg/g na concentração entre cada amostra. Das 20 amostras, 14 foram empregadas para a calibração e 6 para validação. Os espectros foram adquiridos em um espectrômetro NICOLET Magna 550, em duplicata das amostras. Para a construção dos modelos de regressão multivariada, as informações espectrais foram processadas no aplicativo Pirouette® 2.7 da Infometrix, utilizando-se as regiões 3.715-3.088 cm-1 e 1.634 -1.191 cm-1. A calibração foi realizada pelo método de regressão dos mínimos quadrados parciais (PLS), utilizando pré-processamento autoescalado, e tratamento com correção do espalhamento de luz (MSC). Foram selecionados os melhores modelos, considerando os valores do coeficiente de correlação (R²) e da raiz quadrada dos erros médios quadráticos de validação (RMSEV). Os resultados permitem concluir que modelos de calibração, empregando dados DRIFTS e regressão PLS, podem ser empregados como alternativa na dosagem de diclofenaco de potássio, agregando como vantagens frente aos métodos usuais, a não geração de resíduos, a fácil realização da análise e o baixo custo operacional.In this work the alternative method for quantification of potassium diclofenac was studied, using diffuse reflectance infrared Fourier transform spectrocopy (DRIFTS), together with partial least squares regression (PLS). Two spectra of 20 samples with different concentrations (0.15-0.50 mg/g) of potassium diclofenac in starch had been colleted in Nicolet Magna 550 spectrophotometer, with resolution of the 4 cm-1 and 32 scans. For multivariate regression 14 samples had been used for calibration set and 6 samples had been used for validation set. For the PLS modeling, the spectral information (3715-3088 cm-1 and 1634-1191 cm-1) after multiplicative scatter correction (MSC) and autoscaling preprocess, had been processed in Pirouette® 2.7. The best models with better coefficient regression (R²), these were improved using root mean square error of validation (RMSEV). The new technique propose using DRIFTS/PLS shows an excellent choices for the quality control of the productive process of factories and drugstores that produce or handle these materials in large scale, presenting low time of analysis, no sample destruction and no wastes production

Multivariate analysis to applied in the identification of antidepressants. Part II: principal components analysis (PCA) and soft independent modeling of class analogies (SIMCA)

Neste trabalho a identificação e a discriminação de dois diferentes fármacos utilizados como antidepressivos foi estudada, empregando os espectros de reflexão difusa no infravermelho médio com transformada de Fourier (DRIFTS), juntamente com a análise de componentes principais (PCA) e o método de classificação SIMCA. Os espectros no infravermelho de amostras contendo diferentes concentrações dos princípios ativos cloridrato de amitriptilina e cloridrato de imipramina, foram coletados em um espectrofotômetro NICOLET Magna 550, sendo realizadas 2 réplicas para cada amostra, com resolução de 4 cm-1 e 32 varreduras. A análise de componentes principais confirmou a existência de dois grupos distintos, correspondendo aos dois diferentes princípios ativos utilizados, além de evidenciar a presença de amostras anômalas no conjunto de dados que, possivelmente, iriam interferir na modelagem. Já o método de classificação SIMCA possibilitou o reconhecimento de amostras dos princípios ativos cloridrato de imipramina e cloridrato de amitriptilina com resultados indicando 100% de classificação correta das classes modeladas.In this work the certification of two different drugs used as antidepressants was studied, using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), together with the analysis of principal components (PCA) and the method of soft independent modeling of class analogies (SIMCA). The DRIFT spectra of samples with different concentrations of the active principles amitriptiline and imipramine hydrochlorides had been collected in Magna 550 spectrofotometer, two spectra for each sample, with resolution of 4 cm-1 and 32 scans. The PCA confirmed the existence of two distinct groups, corresponding to the two different active principles used. Otherwise the method of classification SIMCA made possible the recognition of samples of the principles amitriptyline and imipramine hydrochlorides with results indicating 100% of correct classification

INCIDÊNCIA DE RESÍDUOS DE PESTICIDAS EM ALIMENTOS PRODUZIDOS EM ÁREAS DE PLANTAÇÃO DE TABACO NA BACIA DO RIO PARDINHO, RS, BRASIL.

The Vale do Rio Pardo region, where the Pardinho River Basin is located, is the main tobacco growing area of Brazil. Tobacco growing involves intense and regular use of pesticides. Among the risks to which producers are exposed is the use of the soil employed in tobacco seedling production for food cultivation. This soil can contain residues from successive pesticide applications. The objective of this work was to verify the possible contamination of these foods, seeking to elucidate the environmental problem related to tobacco growing. Therefore, 147 rural properties with less than 25ha in area, and located within the limits of the Pardinho River Basin, in the municipal districts of Gramado Xavier, Sinimbu and Santa Cruz do Sul, were selected. Of these rural properties, 23 used seedling soil for food cultivation. Residues of acephate, methamidophos, disulfoton, chlorpyrifos, and mancozeb were analyzed in 25 samples, such as sweet potato, cabbage, beans, watermelon, cucumber and tomato. No residues were found in these samples, showing that the families of the considered rural properties, during the 2000/2001 crop season, were not subjected to contamination by consumption of the food crops produced in the tobacco seedling soil.A região do Vale do Rio Pardo, na qual a bacia hidrográfica do Rio Pardinho se insere, caracteriza-se por ser a principal região fumicultora do Brasil. O cultivo do tabaco nesta região envolve o uso intenso e sistemático de pesticidas. Entre os riscos que os produtores estão expostos está a prática de cultivo de alimentos no solo usado para a produção de mudas, o qual pode conter resíduos das sucessivas aplicações de pesticidas. Verificar a possibilidade de contaminação destes alimentos foi o objetivo deste trabalho, visando contribuir para a elucidação da problemática sócio-ambiental relacionada ao cultivo do tabaco, ainda pouco estudada. Para isso, selecionou-se 147 propriedades rurais de até 25ha, localizadas dentro dos limites da bacia hidrográfica do Rio Pardinho, nos municípios de Gramado Xavier, Sinimbu e Santa Cruz do Sul. Destas propriedades, foi verificado que em 23 foram utilizadas as áreas de canteiro de mudas para o cultivo de alimentos. Foram analisados os resíduos dos pesticidas acefato, metamidofós, disulfoton, clorpirifós e mancozeb, em 25 amostras de alimentos provenientes destas propriedades, entre os quais aipim, batata-doce, couve, feijão, melancia, pepino e tomate. As metodologias de análise empregadas foram a de evolução de dissulfeto de carbono para a determinação dos resíduos de mancozeb, e da cromatografia gasosa para os demais princípios ativos. Não foram encontrados resíduos nas amostras analisadas, mostrando que as famílias das propriedades consideradas, durante a safra 2000/2001, não estiveram sujeitas a contaminação pelo consumo dos alimentos produzidos no solo dos canteiros de mudas de tabaco.

Otimization of Transesterification Double Step Process (TDSP) to the production of biodiesel through Doehlert experimental design

In this work, Doehlert experimental design was used to optimize the Transesterification Double Step Process (TDSP) method of methyl soybean oil biodiesel production which starts with a basic catalysis followed by an acidic catalysis. The conversion values were calculated from NMR spectra. Response surface was used to show the results of the interactions between the variables. This experimental design evaluated variables like catalyst and alcohol amount for the basic catalysis and time and temperature for the acidic catalysis. According to results obtained after Doehlert design application the alcohol amount was the main factor that influenced on the basic catalysis but for the acidic catalysis both time and temperature are important and their effects are opposite. It resulted on excellent conversions for both steps obtaining for the basic catalysis about 100% when was used like optimal conditions catalyst amount equal to 0.40 g and volume of methanol equal to 60 mL and for the acidic catalysis about 99% when was used like optimal conditions temperature of 65°C and 90 minutes for reaction time

Influence of monoterpenes in biological activities of Nectandra megapotamica (Spreng.) mez essential oils

Investigating the influence of seasonal variations on biological activities is important for pharmacological studies and metabolic engineering. Therefore, this study was conducted to determine the variation of the chemical composition of essential oils obtained from Nectandra megapotamica leaves, collected at different stages of plant development, as well as its influence on the biological activities. A total of 38 compounds were identified that accounted for 97–99.2% of the chemical composition of the oils. Major differences were observed in the monoterpenic fraction, representing 5.1% of the compounds identified in the productive rest phase to 37.1% in the blooming phase. Bicyclogermacrene and germacrene D were the predominant compounds identified in the oil of all collections. Furthermore, limonene, β-pinene, and spathulenol were identified predominantly in the samples of blooming and fruiting phases. The oils exhibited significant antichemotactic activity and different effects in scavenging the radical 2,2-diphenyl-1-picrylhydrazyl. Variations were also observed in the antifungal activity, with the minimum inhibitory concentrations ranging from 125 to 500 μg/mL. These results demonstrate the influence of monoterpenes, primarily limonene, α-pinene, and β-pinene, on the bioactivities of the oil. Studies investigating the variations in the chemical composition of essential oil may offer a strategy to produce a compound or a group of compounds of interest to industries with a specific pharmacological focus

Chemometric tools and ftir-atr spectroscopy applied in milk adulterated with cheese whey

Brazilian law forbids the addition of cheese whey in milk. However, adulteration with cheese whey is one of the most applied fraud due to its low cost. The detection of this fraud is the quantification of Caseinomacropeptide (CMP). The CMP is a constituent of the whey that can be used as adulteration marker. Thus, an analytical method capable of identifying CMP by Fourier Transform Infrared Spectra (FTIR) was developed using chemometrics methods. Firstly, we attempted to develop an exploratory analysis model by Hierarchical Grouping Analysis (HCA) and Principal Component Analysis (PCA) that indicated similarity between samples of raw milk and semi-skimmed milk. Moreover, in the PCA scores, it was possible to observe a tendency of separation between samples with different concentrations of CMP. Afterwards, multivariate regression models were used for Partial Least Squares (PLS), Partial Least Square with Interval Synergism (siPLS) and Supporting Machines with Least Squares (LS-SVM) to quantify the adulteration in different types of milk by Cheese serum through the CMP. All the models were then compared to each other and the results of the official method with Liquid Chromatography Tandem mass spectrometry (LCMS/MS) analysis used by the Ministry of Livestock and Supply (MAPA). The model LS-SVM, employing the full spectrum, obtained the best result compared to the other models (PLS and siPLS) to quantify the CMP in the milk samples

AVALIAÇÃO DO DESEMPENHO DE ONDALETAS PARA A CONSTRUÇÃO DE MODELOS DE REGRESSÃO MULTIVARIADA EMPREGANDO DADOS DE ESPECTROSCOPIA NO INFRAVERMELHO

Discrete wavelet transform (DWT) Daubecheis was used to compress the dimension of spectral infrared data for determination to the hydroxyl value (OHV) of soybean polyols samples. Spectral data were recorded between 650 and 4000 cm-1 with a 4 cm-1 resolution by Fourier transform infrared spectroscopy (FTIR) coupled with attenuated total reflection (ATR) accessory. Through the models of regression using partial least squares (PLS) and interval partial least squares (iPLS) methods, the performance of each was compared with the original and/or between them. The spectra data set compressed the 1/4 of its original dimension they had presented the best one resulted with a lesser RMSEP that the model with the not compress signal and a similar correlation. With this result a model of lesser dimension was gotten however with the same capacity, thus DWT, getting a robust method for the reduction of the dimension of the spectra data sets, when if to intend to construct regression multivariate models.Neste trabalho utilizou-se a Transformada Discreta Ondaleta (TDO) Daubechies, com 4 coeficientes (Daub4), para compactar a dimensão da matriz de dados espectrais, obtidos por espectroscopia no infravemelho com transformada de Fourier, através da reflectância total atenuada (FTIR-ATR) de amostras de polióis de óleo de soja, visando a determinação do valor de hidroxilas (VOH). Através dos modelos de regressão por mínimos quadrados parciais (PLS), comparou-se o desempenho de cada um dos 5 conjuntos de dados compactados, com o original e/ou entre eles. O conjunto de dados dos espectros de polióis, compactado a 1/4 da sua dimensão original, foi considerado como o mais robusto apresentando um RMSEP 20,28% menor que o modelo com os espectros não compactados e uma correlação semelhante. Esse resultado implicou em um modelo de dimensões menores com a mesma capacidade preditiva, assim a TDO (Daub4), mostra ser um método robusto para a redução da dimensão da matriz de dados espectrais, quando pretende-se construir modelos de regressão multivariados