The solid-phase microextraction (SPME) technique has been widely used due to it is solvent-free characteristic in sampling and analysis. Polydimethylsiloxane (PDMS) is known as an excellent material for the extraction of volatile organic compounds (VOCs). However, there is limited experimental work done to investigate the mass transfer mechanism of VOCs onto PDMS/SPME membranes.
The object of this study was to investigate the adsorption kinetics of benzene and toluene onto PDMS/SPME membranes. Adsorption isotherm of PDMS in the benzene aqueous solution and toluene aqueous solution were obtained using individual batch experiments. The experimental variables were agitation rates and concentrations of aqueous solution.
This study found that the diffusion coefficients of benzene and toluene in PDMS/SPME were linearly increased with agitation rates of aqueous solution (p<0.05). The possible reason may be that the boundary liquid layer around PDMS fiber was shortened by the agitation. On the other hand, the diffusion coefficients were not significantly correlated with the aqueous concentrations (p>0.5). This study could sever as the fundamental work on the mass transfer of VOCs in PDMS, particularly for SPME.
