Optimization and validation of an SBSE-HPLC-FD method using laboratory-made stir bars for fluoxetine determination in human plasma.

Depression is the largest cause of disability worldwide, affecting 350 million people. Notwithstanding that clinical trials demonstrate antidepressants efficacy, the efficient response can vary individually concerning therapeutic dosage. Although important, plasma levels monitoring remains an analytical challenge whereas clean-up and pre-concentration represent critical steps. Therefore, this study aims to develop, optimize and validate a method for fluoxetine determination in human plasma, employing a laboratory-made device consisting of a PDMS stir bar sorptive for extraction, coupled with high-performance liquid chromatography-fluorescence detection (SBSE-HPLC-FD). Optimization involved sorption-desorption steps. For sorption, temperature and time were assessed by factorial and central composite design approaches, taking into account the desirability and the response surface results, with stirring speed also examined. For desorption kinetics and ultrasonic and magnetic stirring mode were evaluated. The proposed method after validation was robust, linear (25.00-1000.00 ng mL-1 , R2 > 0.98) and presented good intra- (RSD 4.18%) and inter-day-assay (RSD 11.60%) precision and accuracy (recovery 109.60%), allowing reliable quantitation without interference. The method was successfully applied to real samples. SBSE-HPLC-FD could represent a feasible alternative with good cost-benefit for low-volume samples and therapeutic drug monitoring, as well as contributing to correlation studies between plasma fluoxetine levels and clinical response, which is still little studied.

Antioxidant activity and estimation of melanoidin content in commercial roasted coffee / Atividade antioxidante e estimativa do teor de melanoidinas em cafés torrados comerciais

Coffee contains several bioactive compounds, highlighting the antioxidants, whose consumption has been correlated with reduced incidence of chronic and degenerative diseases. Among 100 known species of the genus Coffea the most important economically in the international trade are Coffea arabica (arabica coffee) and Coffea canephora (robusta coffee), usually found as blends in commercial products. Arabica coffees present a higher sensory quality. The components associated with the antioxidant activity (AA) of coffee beverages included the class of phenolic compounds (especially 5-CQA) and caffeine, which have been most commonly studied, and melanoidins produced in the roasting process, for whom no data are available in the literature. Different methods are used to characterize the antioxidant capacity of foods, but there is no efficient and universal methodology of measurement. In this paper, roast and ground Brazilian coffees, commercialized under different designations (37 samples) were analyzed for the level of melanoidins, by spectrophotometry, and the antioxidant activity, by ABTS and total phenolics (Folin- Ciocalteau). All the products evaluated showed significant antioxidant activity. Differences observed in the estimation of the content of melanoidins indicated different roasting processes. Considering the different categories, the Gourmet coffees were characterized fo

O café contém vários componentes bioativos, em destaque os antioxidantes, cujo consumo tem sido correlacionado a redução da incidência de doenças crônicas e degenerativas. Dentre aproximadamente 100 espécies conhecidas do gênero Coffea as mais importantes economicamente no mercado internacional são Coffea arabica (café arábica) e Coffea canephora (café conilon), usualmente encontradas como blends em produtos comerciais. O café arábica apresenta melhor qualidade sensorial. Os compostos aos quais é atribuída a atividade antioxidante (AA) das bebidas de café incluem a classe de fenóis (destaque para o 5-ACQ) e cafeína, que têm sido mais usualmente estudados, e melanoidinas, produzidas no processo de torra, para as quais dados na literatura são escassos. Diferentes métodos são utilizados para caracterizar a capacidade antioxidante de alimentos, mas não existe uma metodologia eficiente e universal de medida. Nesse trabalho, cafés torrados e moídos nacionais comercializados com diferentes denominações (37 amostras), foram analisados quanto a concentração de melanoidinas, por espectrofotometria, e atividade antioxidante pelo método ABTS e de fenólicos totais (Folin- Ciocalteau). Todos os produtos avaliados apresentaram expressiva atividade antioxidante, mas observaram-se diferenças na estimativa do teor de melanoidinas, indicando processos de torra diferenciados. Considerando-se as di

Antioxidant activity and estimation of melanoidin content in commercial roasted coffee / Atividade antioxidante e estimativa do teor de melanoidinas em cafés torrados comerciais

Coffee contains several bioactive compounds, highlighting the antioxidants, whose consumption has been correlated with reduced incidence of chronic and degenerative diseases. Among 100 known species of the genus Coffea the most important economically in the international trade are Coffea arabica (arabica coffee) and Coffea canephora (robusta coffee), usually found as blends in commercial products. Arabica coffees present a higher sensory quality. The components associated with the antioxidant activity (AA) of coffee beverages included the class of phenolic compounds (especially 5-CQA) and caffeine, which have been most commonly studied, and melanoidins produced in the roasting process, for whom no data are available in the literature. Different methods are used to characterize the antioxidant capacity of foods, but there is no efficient and universal methodology of measurement. In this paper, roast and ground Brazilian coffees, commercialized under different designations (37 samples) were analyzed for the level of melanoidins, by spectrophotometry, and the antioxidant activity, by ABTS and total phenolics (Folin- Ciocalteau). All the products evaluated showed significant antioxidant activity. Differences observed in the estimation of the content of melanoidins indicated different roasting processes. Considering the different categories, the Gourmet coffees were characterized fo

O café contém vários componentes bioativos, em destaque os antioxidantes, cujo consumo tem sido correlacionado a redução da incidência de doenças crônicas e degenerativas. Dentre aproximadamente 100 espécies conhecidas do gênero Coffea as mais importantes economicamente no mercado internacional são Coffea arabica (café arábica) e Coffea canephora (café conilon), usualmente encontradas como blends em produtos comerciais. O café arábica apresenta melhor qualidade sensorial. Os compostos aos quais é atribuída a atividade antioxidante (AA) das bebidas de café incluem a classe de fenóis (destaque para o 5-ACQ) e cafeína, que têm sido mais usualmente estudados, e melanoidinas, produzidas no processo de torra, para as quais dados na literatura são escassos. Diferentes métodos são utilizados para caracterizar a capacidade antioxidante de alimentos, mas não existe uma metodologia eficiente e universal de medida. Nesse trabalho, cafés torrados e moídos nacionais comercializados com diferentes denominações (37 amostras), foram analisados quanto a concentração de melanoidinas, por espectrofotometria, e atividade antioxidante pelo método ABTS e de fenólicos totais (Folin- Ciocalteau). Todos os produtos avaliados apresentaram expressiva atividade antioxidante, mas observaram-se diferenças na estimativa do teor de melanoidinas, indicando processos de torra diferenciados. Considerando-se as di