Systems and methods for the detection of substances (particularly particulate substances) within mail pieces, specifically letters and other “flats” of mail. In particular, the systems and methods are for the detection of residues of Chemical or Biological Warfare Agents (CBWAs) which may be present...http://www.google.de/patents/US7073371?utm_source=gb-gplus-sharePatent US7073371 - Systems and methods for residue collection
