The development of novel organically modified sol-gel media for use with ATR/FTIR sensing.
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 degrees C increase in the sensing temperature and the use of a predictive Fickian model previously developed by this research group.
Flavin
K
K
Department of Chemical and Life Sciences, Waterford Institute of Technology, Cork Road, Waterford City, Ireland.
Mullowney
J
J
Murphy
B
B
Owens
E
E
Kirwan
P
P
Murphy
K
K
Hughes
H
H
McLoughlin
P
P
D003432:Cross-Linking Reagents / Q000737:chemistry; D004058:Diffusion; D006358:Hot Temperature; D009578:Nitrobenzenes / Q000737:chemistry; D017646:Organosilicon Compounds / Q000737:chemistry; D010575:Pesticides / Q000737:chemistry; D019904:Polymethyl Methacrylate / Q000737:chemistry; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D014867:Water; D014992:Xylenes / Q000737:chemistry
D003432:Cross-Linking Reagents; D009578:Nitrobenzenes; D017646:Organosilicon Compounds; D010575:Pesticides; D012996:Solutions; D014992:Xylenes; C524585:diphenyldimethoxysilane; D014867:Water; C410706:phenyltrimethoxysilane; C031286:4-xylene; D019904:Polymethyl Methacrylate; C010407:4-chloronitrobenzene