Employment of graphene based sorbents in modern sample preparation techniques

Author(s)

Bruno Henrique Fumes

• Document type: Doctoral Thesis
• Press: São Carlos.
• Institution: Universidade de São Paulo (USP). Instituto de Química de São Carlos (IQSC/BT)
• Defense date: 2018-04-06

Examining board members

Fernando Mauro Lanças; Silvia Helena Govoni Brondi; Luiz Henrique Mazo; Anderson Rodrigo Moraes de Oliveira

• Advisor: Fernando Mauro Lanças

Abstract

Modern sample preparation techniques have been applied to the determination of different compounds class in several matrices. These techniques might be divided into two groups, solvent and sorbent based, the last being the goal of this work. Nowadays, among the most studied materials the graphene based ones has been highlighted due to its physical chemical properties favorable to sorption process of a variety of interested compounds. The present work shows possibilities to employ graphene based materials in the follow sample preparation techniques: microextraction by packed sorbent (MEPS), \"on-line\" extraction, and stir bar sorptive extraction (SBSE). For MEPS, the materials graphene oxide and graphene supported on aminopropyl silica through covalent bounds were synthesized. These materials were employed as sorbent to determine parabens in water samples. The developed method showed limits of quantification (LOQ) ranging from 0,2 a 0,3 μg/L, coefficients of variation (CV) < 19,2% and accuracy ranging from 82,3 à 119,2%. The synthetized materials used in MEPS were also used and compared to an \"on-line\" method employing an extraction column packed with them. The \"on-line\" method showed LOQ of 0,5 μg/L, accuracy ranging from 88,2 to 107,2 and CV < 16%. The comparison between packed column with graphene and graphene oxide supported on aminopropyl silica showed that graphene had a higher retention for parabens with high Log Kow. The method developed with SBSE bars coated with graphene showed LOQ ranging from 2 to 8 μg/L, accuracy ranging from 81,9 to 126,3% and CV < 30%. Moreover, the employment of graphene oxide and graphene synthetized by changing some synthesis conditions and testing these materials to extract triazines, sulfonamides, and non-steroidal anti-inflammatory drugs was also evaluated. In addition, are presented the preliminary tests regarding to a new extraction mode, similar to SBSE. These tests were done for parabens and non-steroidal anti-inflammatory drugs. (AU)

• FAPESP's process: 15/15462-5 - Employment of graphene as sorbent in miniaturized sample preparation techniques.
• Grantee: Bruno Henrique Fumes
• Support Opportunities: Scholarships in Brazil - Doctorate