title: Optimization of the HS-SPME-GC-IT/MS method using a central composite design for volatile carbonyl compounds determination in beers.
abstract: An automated headspace solid-phase microextraction (HS-SPME) combined with gas chromatography and ion trap mass spectrometry detection (GC-IT/MS) was developed in order to quantify a large number of carbonyl compounds in beers. Carbonyl compounds were previously derivatized with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA). Volatile carbonyl compounds associated with staling beer aroma includes alkanals, alkenals, alkadienals, dicarbonyl compounds, Strecker aldehydes, ketones and furans. The HS-SPME was performed using a polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber. The procedures were optimized for HS-SPME pre-incubation temperature and time, extraction temperature and time, and PFBHA addition. A central composite design was used in the optimization of extraction conditions and PFBHA addition. The volatile compounds showed optimal extraction incubating 5 ml of beer with 700 mg l(-1) of PFBHA for 7 min and extracted for more 20 min at 45 °C. The method was validated with regard to the linearity, repeatability, inter and intra-day precision and accuracy. The method achieved detection limits ranging from 0.003 to 0.510 µg l(-1), except for furans (1.54-3.44 µg l(-1)). The quantification limits varied from 0.010 to 1.55 µg l(-1), except for 2-furfural (4.68 µg l(-1)), 5-methyl-2-furfural (5.82 µg l(-1)) and 5-hyfroxymethylfurfural (10.4 µg l(-1)). Repeatability values of all compounds were lower than 17%. The method accuracy was satisfactory with recoveries ranging from 88% to 114%. The validated method showed to be suitable for a fast and reliable determination of main carbonyl compounds in beers.
authors.affiliation: REQUIMTE/Laboratório de Toxicologia, Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Rua Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal; CBQF/Centro de Biotecnologia e Química Fina, Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Rua Dr. António Bernardino Almeida, 4200-072 Porto, Portugal. Electronic address: nmoreira@porto.ucp.pt.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Moreira
authors.forename: Sónia
authors.initials: S
authors.lastname: Meireles
authors.forename: Tiago
authors.initials: T
authors.lastname: Brandão
authors.forename: Paula Guedes
authors.initials: PG
authors.lastname: de Pinho
mesh_terms: D000447:Aldehydes / Q000032:analysis*; D001515:Beer / Q000032:analysis*; D004129:Dimethylpolysiloxanes / Q000737:chemistry*; D005163:Factor Analysis, Statistical; D005663:Furans / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry / Q000706:statistics & numerical data; D006801:Humans; D006898:Hydroxylamines / Q000737:chemistry*; D007659:Ketones / Q000032:analysis*; D057230:Limit of Detection; D011145:Polyvinyls / Q000737:chemistry*; D015203:Reproducibility of Results; D052617:Solid Phase Microextraction; D013696:Temperature; D005466:Fluorocarbons
chemical_list: D000447:Aldehydes; D004129:Dimethylpolysiloxanes; D005663:Furans; D006898:Hydroxylamines; D007659:Ketones; D011145:Polyvinyls; C445089:poly(dimethylsiloxane-divinylbenzene); C010277:Florox Reagent; D005466:Fluorocarbons
keywords: Beer; Central composite design (CCD); Gas chromatography–ion trap/mass spectrometry (GC–IT/MS); Headspace solid-phase microextraction (HS-SPME); PFBHA; Volatile carbonyl compounds