Air Sampling with Porous Solid-Phase Microextraction Fibers

Abstract

A new, rapid air sampling/sample preparation methodology was investigated using adsorptive solid-phase microextraction (SPME) fiber coatings and nonequilibrium conditions for volatile organic compounds (VOCs). This method is the fastest extraction technique for air sampling at typical airborne VOC concentrations. A theoretical model for the extraction was formulated based on the diffusion through the interface between the sampled (bulk) air and the SPME coating. Parameters that affect the extraction process including sampling time, air velocity, air temperature, and relative humidity were investigated with the porous (solid) PDMS/DVB and Carboxen/PDMS coatings. Very short sampling times from 5 s to 1 min were used to minimize the effects of competitive adsorption and to calibrate the extraction process in the initial linear extraction region. The predicted amounts of extracted mass compared well with the measured amounts of target VOCs. Findings presented in this study extend the existing fundamental knowledge related to sampling/sample preparation with SPME, thereby enabling the development of new sampling devices for the rapid sampling of air, headspace, water, and soil.

Field measurements of biogenic volatile organic compounds in the atmosphere using solid-phase microextraction Arrow

“…S4). The small effect of relative humidity when using hydrophobic materials has also been observed previously, where the extraction of benzene, toluene, p-xylene, and ethylbenzene with a PDMS-DVB-coated SPME fiber at different humidity showed a maximum reduction of the mass adsorbed by approximately 21 % after 1 h of sampling (Koziel et al, 2000). A small effect of relative humidity on the SPME extraction when using hydrophobic coatings was also shown in another study, where two carbon-based SPME coatings were used for the sampling of 1,1,1-trichloroethane and carbon tetrachloride (Chai and Pawliszyn, 1995).…”

Belowground Chemical Signaling in Maize: When Simplicity Rhymes with Efficiency

“…A 0.2mm diameter cylinder made of ultra-fine metal mesh (2300 mesh; Small Parts Inc., USA) was inserted into the sand, thereby creating a hole in which a solid-phase microextraction (SPME) fiber could be safely inserted. Automated sampling was performed with a 100μm polydimethylsiloxane SPME fiber (Supelco, Buchs, Switzerland) within 12h with a multipurpose sampler (MPS2, Gerstel GmbH & Co. KG, Germany) (Koziel et al 2000;Gorecki and Namiesnik 2002;Vas and Vekey 2004). At 30min intervals, the adsorbed compounds were analyzed by retracting the fiber from the sand and inserting it for 3min in the injector of an Agilent 6890 Series gas chromatograph heated at 230°C (G1530A) coupled to a quadrupole-type mass-selective detector (Agilent 5973; Representative GC-MS chromatograms obtained by sampling just above the two synthetic blends that were used for the diffusion experiments.…”

Calibrant Free Sampling and Enrichment with Solid-Phase Microextraction: Computational Simulation and Experimental Verification

“…[4][5][6] Diffusive sampling is a method in which analytes are collected by an extraction phase (or, extractant) at a rate controlled by molecular diffusion of analytes through the diffusion boundary layer formed around the extractant in the sample matrix. 7,8 It has been shown previously that by exposing a SPME fiber directly to a sample matrix for a short period of time, diffusive sampling can be obtained. This diffusion-based rapid sampling with SPME was introduced with aims to provide a simple and rapid sample analysis method.…”

“…This diffusion-based rapid sampling with SPME was introduced with aims to provide a simple and rapid sample analysis method. 7 To date, different formats of diffusive sampling devices have been applied towards analysis of air and water samples. [9][10][11][12] The requirements for the diffusion-based quantification are: (i) the extractant must behave as a zero sink or perfect sorbent; (ii) the extraction is controlled by diffusion through a diffusion boundary layer formed around the extractant surface, which can be assured by a steady fluid flow condition that maintains an unchanged diffusion-layer thickness; (iii) mass uptake should be linear irrespective of changes to either sampling time or analyte concentration.…”

“…14,15 For quantification with the open bed format, a semi-empirical equation based on the assumption of uniform thickness of the diffusion layer is used to calculate the diffusion layer thickness. 7 However, this method introduces large errors in the calculations, since the diffusion layer thickness is not uniform around the fiber and dependent on the physical dimensions of the fiber coating, sample flow conditions, and the physicochemical properties of the analytes under study. 16 To overcome this drawback, Chen et al 17 proposed a semi-empirical physical model to describe rapid SPME quantification, as shown in eq.1.…”