Patent ID: 7299711

Claim:
A method for controllably releasing contaminants from a contaminated porous metallic mesh during a thermal desorption cycle, comprising: a) providing a contaminated porous metallic mesh in gaseous communication with a chemical detector; b) increasing the temperature of the mesh in a series of at least two stepped temperature rises, by sequentially performing at least two consecutive heating steps, wherein each heating step comprises: 1) applying a heating pulse by resistively heating the mesh for a heating time period by passing an electric current directly through the mesh from one edge of the mesh to an opposite edge of the mesh, thereby generating Joule-type electrical resistance heating directly in the mesh; 2) increasing the temperature of the mesh during the heating pulse and thermally desorbing a batch of contaminant molecules; followed by 3) not heating the mesh for a dwell time period that is at least 2 times longer than the heating time period; and c) carrying the batch of contaminant molecules to the chemical detector for subsequent detection and analysis.