title: Polymeric ionic liquid coatings versus commercial solid-phase microextraction coatings for the determination of volatile compounds in cheeses.
abstract: The extraction performance of four polymeric ionic liquid (PIL)-based solid-phase microextraction (SPME) coatings has been studied and compared to that of commercial SPME coatings for the extraction of 16 volatile compounds in cheeses. The analytes include 2 free fatty acids, 2 aldehydes, 2 ketones and 10 phenols and were determined by headspace (HS)-SPME coupled to gas chromatography (GC) with flame-ionization detection (FID). The PIL-based coatings produced by UV co-polymerization were more efficient than PIL-based coatings produced by thermal AIBN polymerization. Partition coefficients of analytes between the sample and the coating (Kfs) were estimated for all PIL-based coatings and the commercial SPME fiber showing the best performance among the commercial fibers tested: carboxen-polydimethylsyloxane (CAR-PDMS). For the PIL-based fibers, the highest K(fs) value (1.96 ± 0.03) was obtained for eugenol. The normalized calibration slope, which takes into account the SPME coating thickness, was also used as a simpler approximate tool to compare the nature of the coating within the determinations, with results entirely comparable to those obtained with estimated K(fs) values. The PIL-based materials obtained by UV co-polymerization containing the 1-vinyl-3-hexylimidazolium chloride IL monomer and 1,12-di(3-vinylimiazolium)dodecane dibromide IL crosslinker exhibited the best performance in the extraction of the select analytes from cheeses. Despite a coating thickness of only 7 µm, this copolymeric sorbent coating was capable of quantitating analytes in HS-SPME in a 30 to 2000 µg L(-1) concentration range, with correlation coefficient (R) values higher than 0.9938, inter-day precision values (as relative standard deviation in %) varying from 6.1 to 20%, and detection limits down to 1.6 µg L(-1).
authors.affiliation: Departamento de Química Analítica, Nutrición y Bromatología, Universidad de La Laguna (ULL), La Laguna 38206, Tenerife, Spain. Electronic address: mtrujill@ull.es.
authors.forename: María J
authors.initials: MJ
authors.lastname: Trujillo-Rodríguez
authors.affiliation: Department of Chemistry, School of Green Chemistry and Engineering, The University of Toledo (OH), Toledo, OH 43606, USA. Electronic address: Honglian.Yu@rockets.utoledo.edu.
authors.forename: Honglian
authors.initials: H
authors.lastname: Yu
authors.affiliation: Department of Chemistry, School of Green Chemistry and Engineering, The University of Toledo (OH), Toledo, OH 43606, USA. Electronic address: William.Cole3@rockets.utoledo.edu.
authors.forename: William T S
authors.initials: WT
authors.lastname: Cole
authors.affiliation: Department of Chemistry, School of Green Chemistry and Engineering, The University of Toledo (OH), Toledo, OH 43606, USA. Electronic address: Tien.Ho@rockets.utoledo.edu.
authors.forename: Tien D
authors.initials: TD
authors.lastname: Ho
authors.affiliation: Departamento de Química Analítica, Nutrición y Bromatología, Universidad de La Laguna (ULL), La Laguna 38206, Tenerife, Spain. Electronic address: veropino@ull.edu.es.
authors.forename: Verónica
authors.initials: V
authors.lastname: Pino
authors.affiliation: Department of Chemistry, School of Green Chemistry and Engineering, The University of Toledo (OH), Toledo, OH 43606, USA. Electronic address: Jared.Anderson@UToledo.edu.
authors.forename: Jared L
authors.initials: JL
authors.lastname: Anderson
authors.affiliation: Departamento de Química Analítica, Nutrición y Bromatología, Universidad de La Laguna (ULL), La Laguna 38206, Tenerife, Spain. Electronic address: aafonso@ull.es.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Afonso
mesh_terms: D002611:Cheese / Q000032:analysis*; D052578:Ionic Liquids; D011108:Polymers / Q000737:chemistry*; D052617:Solid Phase Microextraction / Q000379:methods*; D055549:Volatile Organic Compounds / Q000032:analysis*
chemical_list: D052578:Ionic Liquids; D011108:Polymers; D055549:Volatile Organic Compounds
keywords: Gas-chromatography; Ionic liquids; Polymeric ionic liquids; Solid-phase microextraction; Volatile compounds