Analytical Sciences

Abstract − Analytical Sciences, 14(1), 209 (1998).

Detection of Organic Molecules Dissolved in Water Using ag-Al2O3 Chemiluminescence-Based Sensor
Masuo NAKAGAWA*, Isao YAMAMOTO** and Nobuhiko YAMASHITA***
*Faculty of Science, Okayama University ofScience, Ridai-cho, Okayama 700, Japan
**Faculty of Engineering, Okayama University of Science, Ridai-cho, Okayama700, Japan
***Faculty of Education, Okayama University, Tsushima-naka, Okayama 700,Japan
A new method is proposed for recognizing organic molecules dissolved inwater using a chemiluminescence-based sensormade with a g-Al2O3 catalyst. When a mixture of air and organicmolecules, e.g. ethanol and acetone vaporized from asolution, flows around the sensor, chemiluminescence (CL) is emitted duringits catalytic oxidation. The CL spectraconsist of subbands peaking at the same wavelengths independent of the typeof vapors. The peak wavelengths of thesesubbands are the same as those for CL with a CaCO3catalyst. The relative CL intensity of each band,however, dependson the type of the vapor and the temperature of the sensor. This impliesthat CL originates in the same kinds of luminousspecies produced during the course of catalytic oxidation. By keeping asample gas around the sensor in a state oflaminar flow and by keeping the catalytic oxidation on the sensor under thediffusion-controlled condition, the CLintensity becomes stable and reproducible. The CL intensity is proportionalto the concentration of these organic vaporsin the gas phase within the concentration range of from 1 - 500 ppm. (Keywords: Chemiluminescence, sensor, catalytic oxidation, organicmolecules, aluminum oxide)