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Low volatility substance detection by an electrochemical sensor - involves detecting a cathodic current maximum and measuring the current potentiostatically until saturation.
: Krausa, M.; Schorb, K.; Krebs, S.; Becker, F.

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DE 1997-19748124 A: 19971031
DE 1997-19748124 A: 19971031
EP 1998-119670 A: 19981017
DE 19748124 C1: 19990318
EP 913687 B1: 20041229
Patent, Elektronische Publikation
Fraunhofer ICT ()

NOVELTY - Low volatility substances are detected in soil, liquids and gases by carrying out several electrochemical sensor measuring cycles of applied voltage increase and decrease, determining the current difference of successive cycles and, if a cathodic current maximum occurs, determining the associated voltage value and measuring the current intensity potentiostatically over the time to saturation. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a sensor element for detecting low volatility substances, the sensor element (1) including work electrodes (3) in the form of micro-electrodes and an electrolyte (5) in the form of a thin layer applied to the sensor element front face which is in contact with the substance to be detected. Preferred Features: The potential range in each measuring cycle extends between the hydrogen and oxygen evolution values. The detected values may be output optically or acoustically. The substance to be detected is passed by the sensor ele ment and, when gaseous, may be pumped through a flow-through cell on the sensor element. The electrolyte is a viscous or gel-like organic and/or inorganic electrolyte. USE - Especially for detecting nitrotoluene, trinitrotoluene, dinitrotoluene, nitrotoluene derivatives and chemical warfare agents (e.g. Clark agent, Lewisite, mustard agent, Sarin, Soman, Tabun or the like) in soil, liquids and gases, e.g. for luggage and passenger checking at airports and for mine detection. ADVANTAGE - The method produces a characteristic cathodic current peak for the substance to allow rapid (e.g. a response time of less than 0.5 sec.) and reliable, qualitative and quantitative detection of electrochemically reactive substances even at very low concentrations and/or vapor pressures.