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Optical UV-Derivative-Spectroscopy for Monitoring Gaseous Emissions

Optische UV-Derivativ-Spektroskopie für die Überwachung von Gasemissionen
: Vogt, F.; Klocke, U.; Rebstock, K.; Schmidtke, G.; Wander, V.; Tacke, M.


Applied spectroscopy 53 (1999), No.11, pp.1352-1360
ISSN: 0003-7028
Journal Article
Fraunhofer IPM ()
Optical UV Derivative-Spectroscopy; on-line monitoring; gaseous emissions; chemometric methods

UV Derivative Spectroscopy is investigated for its potential in on-line control of various processes. One typical application is emission monitoring of several pollutants like SO2, NO, NO2, NH3, and aromatic hydrocarbons. The proposed method gains selectivity and sensitivity by using the first and second derivative of the transmission spectrum with respect to wavelength. These derivatives are generated in an optical manner and are compared empirically for the first time with the known numerical derivative spectroscopy and conventional transmission spectroscopy. The generation of the optical derivatives is discussed. For demonstration of the feasibility, laboratory monitoring results are reported. Using a sample pathlength of 10cm with this optical method detection limits are determined to be 4ppm compared to 11ppm with numerically calculated signals and 20ppm obtained by using the transmission only. Typically a time resolution of below three minutes is achieved. Emphasis is laid also on the treatment Emphasis and appearing nonlinearity by means of chemometric calibration and evaluation algorithm like Principal Component Regression (PCR) and Partial Least Squares (PLS).