Abstract: An apparatus for the detection of airborne, low volatility materials, comprising a mobile carrier, preferably made of silica, onto which material to be detected is caused to be deposited. The mobile carrier is arranged to carry the material to the first location where unwanted volatile materials are purged from the trap, then to a second location where the remaining material is caused to be ionized and then to a third location where the ionized material is caused to be lifted off the carrier into an ion collector.