Thin-film molecularly imprinted polymers for detection systems for polycyclic aromatic hydrocarbons in water

摘要

Thin-film molecularly imprinted polymers (MIPs) are smart materials that selectively uptake specific compounds from complex matrices based on molecular recognition principles. These materials can be applied for monitoring of organic pollutants such as polycyclic aromatic hydrocarbons (PAHs) in water as an early indicator of oil spills. MIPs are sometimes prepared in presence of a template that resembles the analyte (not the actual analyte), also referred to as a pseudo-template, to avoid issues with template bleed and associated false-positive results. This thesis describes the first account of thin-film MIPs for light PAHs using toluene as a pseudo-template. The procedure is very simple, fast and uses low-tech equipment. Detection is carried out offline using gas chromatography-mass spectrometry and fluorescence. As the role of each component in the MIP is discussed and recognized, various compositions were tested for sensitivity and selectivity. Several types of MIPs using toluene and phenanthrene-d10 as pseudo-templates, and toluene as a pseudo-template and solvent (porogen) have been further characterized and validated. The composition has been optimized for each MIP; this involved experimental design at earlier stages. The selectivity and sensitivity of the various PAHs are discussed in terms of binding interactions, and the different chemistries of the targeted PAHs. Most characterization and validation tests were carried out in pure water; though high selectivity and remarkable sensitivity were determined in complex wastewater and seawater matrices with no prior sample treatment. Calibration was shown to be possible in seawater matrices such that the MIPs could readily be used for accurate quantification measurements of PAHs.udThe thin-film MIP format has the potential for easy integration into a microfluidic device for on-site on-line monitoring. Such a device would be easily used even by an in-experienced operator. In preliminary work to fabricate such a device, prototyping work was carried out and included patterning channels and reservoir features in polydimethylsiloxane (PDMS) using various soft lithography low-tech methods, and etching electrodes on indium tin oxide (ITO) coated glass slides to create electrode pads. This is necessary to induce current flow, which would ensure continuous sample exposure to the MIP surface, with separation by electrokinetic chromatography with spectroscopic detection or by mass spectrometry, e.g. electrospray ionization- or desorption electrospray ionization-mass spectrometry.