Theory of analyte extraction by selected porous polymer SPME fibres†

Development of headspace solid-phase microextraction-gas chromatography–mass spectrometry methodology for analysis of terpenoids in Madeira wines

“…C 0 is the initial concentration of the flavour compound in the sample, and V 1 , V 2 and V 3 are the volumes of SPME coating, sample volume and the headspace volume, respectively. K air-fibre is the partition coefficient of the flavour compounds between the SPME coating and the headspace; K sample-air is the headspace and the sample partition coefficient The PDMS and PA fibres extract analytes via absorption [42]. The remaining coatings, including PDMS-DVB, Carbowax-DVB, and Carboxen are mixed coatings, in which the primary extracting phase is a porous solid, extracting analytes via adsorption.…”

Factors affecting solid phase microextraction (SPME) to concentrate the odorants of Chinese white salted noodles for GC–MS analysis

“…Obviously, the microscopic adsorption isotherm (assuming a Langmuir model: Górecki et al, 1999) is involved in the dynamic equilibrium among kC p(0) exp[−λt], which is actually equivalent to Q 1 at t = 0, and Q 2 and Q 3 as shown in our macroscopic model (equations 7 and 10).…”

“…Such an inherent physical property could cause water molecules to be adsorbed as well. Hence, in reality, water molecules can also act as kinetically competitive adsorbates, and in the long run their porosities (in the case of Carboxen) or functionalities (in the case of PDMS) 10 are able simultaneously to adsorb the odorant and water molecules, leading to some dead spaces when occupied by the water molecules, a phenomenon usually termed 'capillary condensation', as represented by the fibre CAR/PDMS, 12,14 or 'intermolecular perturbation' in the case of PDMS, which may significantly reduce the adsorption capability of these fibres for odorants. Such a deactivation often occurs multiply as a time-, temperature-and water vapour-dependent phenomenon.…”

“…It has been documented elsewhere that although CAR/ PDMS is superior to PDMS/DVB in adsorption for volatile compounds, the drawback is its poor reproducibility. [17][18][19][20] Although PDMS/DVB favours the adsorption of molecules with medium polarity, it has been reported 10,16,17 that CAR/PDMS is better for adsorption of those substances with low polarity as well as low molecular weight, such as most of the odorants. Hence CAR/PDMS was selected for performing SPME in this study.…”

“…A very successful approach to odorant sample preparation is solid-phase microextraction (SPME), which has the advantages of fast and easy handling, minute sample quantity, cost efficiency of the facility and solventfree extraction. The adsorbates were then analysed with GC and GC-MS. 9,10 Recently, this technique has been adopted to access the volatile constituents in rice. [11][12][13] This study utilized the SPME technique plus GC and GC-MS to survey the flavour and odorants of CWSN, including the optimum adsorption fibre, adsorption time and temperature, with an aim to expand the noodle market by carefully controlling pleasant tastes and flavours.…”