title: Use of graphene supported on aminopropyl silica for microextraction of parabens from water samples.
abstract: 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™-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 NaCl). A factorial design 26-2was 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 NaCl% on the extraction performance. The optimized method achieved a linear range of 0.2-20μg/L for most parabens; weighted calibration models were employed during the linearity evaluation to reduce the absolute sum of the residue values and improve R2, 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.
authors.affiliation: University of São Paulo, São Carlos, Institute of Chemistry of São Carlos, SP, Brazil.
authors.forename: Bruno Henrique
authors.initials: BH
authors.lastname: Fumes
authors.affiliation: University of São Paulo, São Carlos, Institute of Chemistry of São Carlos, SP, Brazil. Electronic address: flancas@iqsc.usp.br.
authors.forename: Fernando Mauro
authors.initials: FM
authors.lastname: Lanças
mesh_terms: D004784:Environmental Monitoring / Q000295:instrumentation* / Q000379:methods*; D006108:Graphite / Q000737:chemistry; D010226:Parabens / Q000032:analysis / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D012822:Silicon Dioxide / Q000737:chemistry*; D052617:Solid Phase Microextraction / Q000295:instrumentation*; D012997:Solvents / Q000737:chemistry; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000302:isolation & purification
chemical_list: D010226:Parabens; D012997:Solvents; D014874:Water Pollutants, Chemical; D014867:Water; D012822:Silicon Dioxide; D006108:Graphite
keywords: Graphene; Graphene oxide; HPLC–MS/MS; Microextraction by packed sorbent (MEPS); Parabens; Water samples