The use of headspace solid phase microextraction for the characterization of volatile compounds in olive oil matrices

Abstract

a b s t r a c tTwo different fibre coatings, for solid phase microextraction (SPME) sampling, poly(dimethylsiloxane) (PDMS) and poly(acrylate) (PA), were studied in order to test, for olive oil matrixes, two mathematical models that relate the directly proportional relationship between the amount of analyte absorbed by a SPME fibre and its initial concentration in the sample matrices. Although the PA fibre was able to absorb higher amounts of compounds from the olive oil sample, the equilibrium was reached later then with the PDMS fibre. In both cases, the amount of analyte present affected the time profile or the equilibrium time in two of the concentrations studied, 0.256 L/kg, 2.56 L/kg and for 2-ethylfuran, pentan-3-one, pent-1-en-3-one, hexanal, trans,trans-non-2,4-dienal and in the four concentrations studied, 0.256 L/kg, 2.56 L/kg, 6.25 L/kg and 400 L/kg, for 4-methyl-pent-3-en-2-one, 2-methylbutan-1-ol, methoxybenzene, hexan-1-ol, cis-hex-3-en-1-ol, trans-hex-2-en-1-ol, 2-ethyl-hexan-1-ol and trans,transdec-2,4-dienal. Comparing the mathematical models of both fibres, the PA-coated fibre showed direct proportionality between the initial concentration and amount extracted, that allows the possibility of relative quantification in a non-equilibrium state in non-aqueous media. The same was not observed for the PDMS fibre.

Comprehensive two-dimensional gas chromatography for fingerprint pattern recognition in olive oils produced by two different techniques in Portuguese olive varieties Galega Vulgar, Cobrançosa e Carrasquenha

“…Several studies have been carried out comparing aroma compounds, oxidative stability, phenolic compounds, odour and other chemical parameters [9][10][11][12]. The novel analytical scale headspace technique of solid phase micro-extraction (SPME) [13] has become a popular, simple, solvent free method for headspace analysis, allowing quantification in both equilibrium and non-equilibrium situations [14,15]. A wide variety of coated fibres offering some degree of sampling selectivity made it a simple, quick, sensitive and versatile method of sample preparation [15][16][17][18][19][20], even for enantiomeric-GC (e-GC) [21].…”

“…The novel analytical scale headspace technique of solid phase micro-extraction (SPME) [13] has become a popular, simple, solvent free method for headspace analysis, allowing quantification in both equilibrium and non-equilibrium situations [14,15]. A wide variety of coated fibres offering some degree of sampling selectivity made it a simple, quick, sensitive and versatile method of sample preparation [15][16][17][18][19][20], even for enantiomeric-GC (e-GC) [21]. Nevertheless, careful experimental procedure and prudent data handling is required.…”

Olive Oil Composition: Volatile Compounds

“…The main advantage of this technique is its simplicity, although a special injection system is mandatory, which can be expensive. When SPME was introduced (Belardi & Pawliszyn, 1989;Arthur & Pawliszyn, 1990) several authors have focused their attention on adapting the technique for aroma compounds analysis (D'Auria et al, 2004;Vichi et al, 2003;Vichi et al, 2005;Ribeiro et al, 2008). The main advantages of this technique are: a) it does not involve sample manipulations; b) it is an easy and clean extraction method able to include, in just one step, all the steps usually needed for aroma extraction.…”

“…There are several coatings commercially available. Polydimethylsiloxane (PDMS) and polyacrylate (PA) coatings extract the compounds by means of an absorption mechanism (Ribeiro et al, 2008) whereas PDMS is a more apolar coating then PA. Polydimethylsiloxane/divinylbenzene (PDMS/DVB), polydimethylsiloxane/carboxene (PDMS/CAR), carbowax/divinylbenzene (CW/DVB), and divinylbenzene/carboxene/polydimethylsiloxane (DVB/CAR/PDMS) extract by an adsorptive mechanism. These second group of fibres have usually a lower mechanic stability but present higher efficiency to extract compounds with low molecular weight (Augusto et al, 2001).…”

“…Time and temperature are also very important issues to take in consideration, since they will affect equilibrium (Vas & Vékey, 2004) and thus extraction efficiency. Methods that consider quantification in nonequilibrium have also been developed (Ai, 1997;Ribeiro et al, 2008). In order to optimize the extraction procedures by HS-SPME, the efficiency, accuracy and precision of the extraction is also directly dependent on operational parameters like extraction time, sample agitation, pH adjustment, salting out, sample and/or headspace volume, temperature of operation, adsorption on container walls and desorption conditions (Pawliszyn, 1997).…”