Analytische Chemie
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- Gas standard preparation (1) (entfernen)
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Pollution through emission of toxic gases becomes an increasing problem for the environment in agricultural, industrial and urban areas. In future, environmental emissions as well as ambient air must be monitored at even lower concentrations as nowadays. Consequently, demands arouse for measuring concentrations as low as the lower ppm or even ppb range. Current state-of-the-art technologies, as for instance electrochemical sensors, have reached their limits in this regard.
The developed ammonia gas standard generator produces standard gas mixtures which comply with the metrological traceability for ammonia gas standards in the desired environmentally relevant measurement range of e. g. 0.5 to 500 nmol/mol. This gas standard preparation method is based on the permeation of ammonia through a membrane at a constant temperature as well as the mixing of this permeated gas with a carrier gas to adjust a gas standard of known concentration. The ammonia gas standard is suitable for the calibration of standard optical methods, e. g cavity ring-down spectroscopy (CRDS) and multi-gas sensors.
The detection of gaseous ammonia in the lower ppm or even ppb range is obtained by incorporation of a fluorescent dye, which shows fluorescence enhancement in the presence of the analyte, into a polymer support being responsible for the accumulation of the analyte. The use of optical fluorescence as transduction mechanism enables high sensitivity as well as high temporal resolution. Here, we present first results on such a sensor system including the use of the developed gas standard generator for calibration issues. Additional benefits, particularly of fluorescence-based sensors, are their capability for miniaturization and potential multiplex mode. Beside the development of a highly sensitive and selective sensor, the integration of such systems into mobile sensor devices is addressed.
These sensors and sensor systems are developed and will be validated and operated in form of functional models for the application areas, structure-integrated sensors and mobile multi-gas sensors.