No abstract

The existing solid-phase microextraction (SPME) kinetic calibration technique, using the desorption of the preloaded standards to calibrate the extraction of the analytes, requires that the physicochemical properties of the standard should be similar to those of the analyte, which limited the application of the technique. In this study, a new method, termed the one-calibrant kinetic calibration technique, which can use the desorption of a single standard to calibrate all extracted analytes, was proposed. The theoretical considerations were validated by passive water sampling in laboratory and rapid water sampling in the field. To mimic the variety of the environment, such as temperature, turbulence, and the concentration of the analytes, the flow-through system for the generation of standard aqueous polycyclic aromatic hydrocarbons (PAHs) solution was modified. The experimental results of the passive samplings in the flow-through system illustrated that the effect of the environmental variables was successfully compensated with the kinetic calibration technique, and all extracted analytes can be calibrated through the desorption of a single calibrant. On-site water sampling with rotated SPME fibers also illustrated the feasibility of the new technique for rapid on-site sampling of hydrophobic organic pollutants in water. This technique will accelerate the application of the kinetic calibration method and also will be useful for other microextraction techniques.

In this research, field samplers are developed using polydimethylsiloxane (PDMS) thin-film as the extraction phase. This technique is based on a similar theory, the solid-phase microextraction (SPME) technique. More specifically, the development of the field sampler involves cutting a section of PDMS thin-film into a specific size and shape, and mounting it onto a stainless steel wire (the handle). The thin-film is then placed into a protective copper cage prior to deployment to prevent biofouling. Kinetic calibration or equilibrium calibration with the standards in the extraction phase is used to introduce an isotopically labeled internal standard for on-site calibration. The initial loading of the standard onto the thin-film and the amount of standard remaining on the thin-film are determined using gas chromatography-mass spectrometry and subsequently used to estimate the concentration of the target analytes. In addition, the field samplers are deployed in the field at two locations (the Meuse River in Eijsden, The Netherlands from April to May, 2005 and Hamilton Harbour located at the western tip of Lake Ontario, ON, Canada from September to December, 2006). Polycyclic aromatic hydrocarbons are identified, and concentrations of fluoranthene and pyrene are estimated in the low ng/L range. The results from both sampling sites are within the expected ranges for environmental samples. This polymeric extraction phase has a high surface-to-volume ratio compared with SPME, which results in higher sensitivity and mass uptake, leading to the detection of lower levels of analytes that many other techniques are unable to achieve.