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Remote and automated detection of organic compounds in subsurface aquifers is crucial to superfund monitoring and environmental remediation. Current monitoring techniques use expensive laboratory instruments and trained personnel. The use of a filled tubular preconcentrator combined with a chemicapacitive detector array presents an attractive option for the unattended monitoring of these compounds. Five preconcentrator materials were exposed to common target compounds of subsurface remediation projects (1,1,2-trichloroethane, trichloroethylene, t-1,2-dichloroethylene, benzene, and perchloroethylene). Rapid heating of the tube caused the collected, concentrated effluent to pass over the surface of a chemicapacitive detector array coated with four different sorbent polymers. A system containing a porous ladder polymer and the sensor array was subsequently used to sample the analytes injected onto sand in a laboratory test, simulating a subsurface environment. With extended collection times, effective detection limits of 5 ± 3 ppbV for 1,1,2-trichloroethane and 145 ± 60 ppbV for benzene were achieved. Effects of the preconcentrator material structure, the collection time, and sensor material on the system performance were observed. The resultant system presents a solution for remote, periodic monitoring of chlorinated organic compounds and other volatile organic compounds in a soil matrix. 相似文献
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Methyl salicylate (MeS) is used as a chemical warfare agent simulant to test chemical protective garments and other individual personal protective gear. The accurate and real-time detection of this analyte is advantageous for various testing regimes. This paper reports the results of MeS vapor exposures on polymer-filled capacitance-based sensors at temperatures ranging from 15 °C to 50 °C under dry and humid conditions. Multiple capacitors were arranged in an array on a silicon chip each having a different sorptive polymer. The sensors used parallel-plate electrode geometry to measure the dielectric permittivity changes of each polymer when exposed to water and MeS vapor. Of the four polymers tested against MeS, the optimal polymer displayed near or sub-parts-per-million detection limits at 35 °C (0–80%RH). 相似文献
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Patel Sanjay V. Hobson Stephen T. Cemalovic Sabina Mlsna Todd E. 《Journal of Sol-Gel Science and Technology》2010,53(3):673-679
The responses of alkylamine functionalized organic bridged polysilsesquioxanes on chemicapacitive sensors to carbon dioxide
(CO2) are described operating at temperatures ranging from 15 to 50°C. These hybrid organic–inorganic network materials were synthesized
by the sol–gel polymerization of a mixture of a matrix monomer and functional monomer at various ratios followed by aging
and ink-jet deposition of the sol on each capacitive sensor. During exposure of the sensor to known concentrations of analyte,
the material’s capacitance was measured. From these changes in capacitance, detection limits ranging from 40 to 100 ppm were
calculated. Furthermore, a correlation was observed with increasing length of the alkyl chain in the amine monomer correlating
with an increase in CO2 sensitivity and a decrease in water sensitivity. These materials offer a new method for CO2 detection for building control systems or other low-power applications using low operating temperatures. 相似文献
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