Determinação direta de Trans- Resveratrol em plasma humano usando Espectroflurimetria e adição-padrão de segunda ordem

Abstract

Trans-resveratrol is an antioxidant found mainly in red grapes and their derivatives. Many works have recently related its intake with the reduction of cardiovascular diseases, LDL cholesterol levels and cancer incidence. This work developed a new spectrofluorimetric method for direct determination of transresveratrol in human plasma by using the second order advantage, which allows analyte determination in the presence of unexpected interferences and is provided by parallel factor analysis (PARAFC). For each measurement, excitation-emission matrices were obtained from 280 to 360 nm (excitation) and from 380 to 550 nm (emission). The strategy adopted in this work combined the data treatment with PARAFAC, for extracting the pure analyte signal, with the standard addition method, which permits determinations in the presence of a strong matrix effect caused by plasma analyte-protein binding. Plasma samples were diluted ten times and for each one four standard additions of trans-resveratrol were performed, in triplicates. A specific PARAFAC model was built for each triplicate of each sample, from three-way arrays formed by 5 measurements (samples plus 4 additions), 17 excitation wavelengths and 86 emission wavelengths. The best models were selected with four factors and accounted for more than 99.90% of the data variance. The obtained loadings were related to trans-resveratrol and three interferences. The scores related to the analyte were used for linear regressions and all standard addition curves presented correlation coefficients equal or largest than 0.99. Good results were obtained in the concentration range from 0.10 to 5.00 µg mL-1, with a recovery between 95.5 and 110.0%. The proposed method was also validated through the estimates of figures of merit, such as sensitivity, analytical sensitivity, selectivity, precision, and limits of detection and quantitation.