▎ 摘　　要

This paper describes the synthesis, characterization and use of graphene supported on aminopropyl silica through covalent bonds (Si-G) as a sorbent for microextraction by packed sorbent (MEPS). Five parabens (methyl, ethyl, propyl, butyl and benzyl) present in water matrices were used as model compounds for this evaluation. The Si-G phase was compared to other sorbents used in MEPS (C18 and Strata(Tm)-X) and also with graphene supported on primary-secondary amine (PSA) silica, where Si-G showed better results. After this, the MEPS experimental parameters were optimized using the Si-G sorbent. The following variables were optimized through univariate experiments: pH (4,7 and 10), desorption solvent (ACN:MeOH (50:50), ACN:H2O (40:60), MeOH and ACN) and ionic strength (0, 10 and 20% of NaCI). A factorial design 2(6-2) was then employed to evaluate other variables, such as the sample volume, desorption volume, sampling cycles, wash cycles and desorption cycles, as well as the influence of NaCI% on the extraction performance. The optimized method achieved a linear range of 0.2-20 mu g/L for most parabens; weighted calibration models were employed during the linearity evaluation to reduce the absolute sum of the residue values and improve R-2, which ranged from 0.9753 to 0.9849. The method's accuracy was 82.3-119.2%; precision, evaluated as the coefficient of variance for intraday and interday analysis, ranged from 1.5 to 19.2%. After evaluation of the figures of merit, the method was applied to the determination of parabens in water samples. (C) 2017 Elsevier B.V. All rights reserved.