Examinando por Autor "L. Silva, Catarina"

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An improved and miniaturized analytical strategy based on μ-QuEChERS for isolation of polyphenols. A powerful approach for quality control of baby foods
(Elsevier, 2018-02-22) Casado, Natalia; Perestrelo, Rosa; L. Silva, Catarina; Sierra, Isabel; S. Câmara, José
An improved and miniaturized quick, easy, cheap, effective, rugged and safe (μ-QuEChERS) strategy combined with ultra-high pressure liquid chromatography coupled to a photodiode array detection system (UHPLC-PDA) was developed and optimized for the determination of twelve polyphenols in different baby foods samples. The proposed analytical approach proved to be highly cost-effective and environmentally friendly, since it showed good extraction efficiency using few amounts of sample (0.3 g), organic solvents (1000 μL), clean-up sorbents (87.5 mg) and partitioning salts (0.2 g), producing minimal waste disposal and reducing analysis time. Method performance was validated in terms of selectivity, linearity, limits of detection and quantification, matrix effects, precision and accuracy using different baby food matrices according to their composition. The overall average recoveries ranged from 71 to 100% with relative standard deviations lower than 6% (n = 18). The method was successfully applied to commercial baby food samples (including pureed solids, juices and porridges), and their total phenolic content (TPC) and antioxidant capacity (RSA) were also investigated. Results allowed characterizing the abundance of the selected polyphenols in the samples, and the highest RSA and TPC were found in the fruit-based baby foods. Thus, this work represents a first approach to determine the nutritional quality of these products.
Comparison of high-throughput microextraction techniques, MEPS and -SPEed, for the determination of polyphenols in baby food by ultrahigh pressure liquid chromatography
(Elsevier, 2019-04-10) Casado, Natalia; Perestrelo, Rosa; L. Silva, Catarina; Sierra, Isabel; S. Câmara, José
In this study, two different high-throughput microextraction techniques, microextraction by packed sorbents (MEPS) and micro solid phase extraction (μ-SPEed®), were evaluated and compared, regarding the performance criteria, for the isolation of polyphenols from baby foods prior to their determination by ultrahigh pressure liquid chromatography (UHPLC). To achieve the best performance, influential parameters affecting extraction efficiency (including type of sorbent, number of extraction cycles, pH, elution solvent and elution volume) were systematically studied and optimized. To enable an effective comparison, selectivity, linear dynamic range, method detection (LODs) and quantification limits (LOQs), accuracy, precision and extraction yields, were determined and discussed for both techniques. Both methods provided the analytical selectivity required for the analysis of polyphenols in baby foods. However, μ-SPEed® sample treatment in combination with UHPLC-PDA has demonstrated to be more sensitive, selective and efficient than MEPS. Appropriate linearity in solvent and matrix-based calibrations, very low LODs and LOQs, ranging between 1.37 and 13.57 μg kg−1 and 4.57 – 45.23 μg kg−1, respectively, suitable recoveries (from 67 to 97%) and precision (RSD values < 5%) were achieved for the selected analytes by μ-SPEed®/UHPLC-PDA. Finally, the validated methodologies were applied to different commercial baby foods. Gallic acid, chlorogenic acid, epicatechin, ferulic acid, rutin, naringenin and myricetin are the most dominant polyphenols present in the studied baby food samples. The proposed methodology revealed a promising approach to evaluate the nutritional quality of this kind of products.