Abstract
The ability to prepare and develop novel pre-concentration media by the sol-gel process, and their integration with mid-infrared transparent waveguides has been demonstrated. This research approach resulted in a mid-infrared sensing methodology in which the properties (porosity, functionality, polarity, etc.) of the recognition layer could be tailored by variation of the sol-gel precursors and processing conditions. Cross-linker type and concentration notably influenced p-xylene absorption and diffusion rate. Unreacted silanol groups appeared to be the dominant factor in the hydrophobicity of sol-gel layers. Variation of sol-gel precursors and thermal treatment altered both film cross-link density and polarity, as demonstrated by variation in the rate of analyte diffusion and equilibrium analyte concentration. The use of a novel 1: 1 PTMOS: DPDMS material as pre-concentration medium in this analytical sensing approach was validated through the determination of p-nitrochlorobenzene in an aqueous environment. The response demonstrated linearity between 0-30 mg L -1 with a correlation coefficient of 0.989 and a limit of detection of 0.7 mg L-1. Sensing times for p-nitrochlorobenzene were also reduced from several hours to 24 minutes, without loss of measurement accuracy or sensitivity, by a 10°C increase in the sensing temperature and the use of a predictive Fickian model previously developed by this research group.
Original language | English |
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Pages (from-to) | 224-229 |
Number of pages | 6 |
Journal | Analyst |
Volume | 132 |
Issue number | 3 |
DOIs | |
Publication status | Published - 2007 |