A detector apparatus having a detector for detecting trace amounts of materials of interest carried into the detector through a detector inlet on a stream of air, the detector apparatus comprising traps formed from a material for collecting said materials of interest, a desorber having an inlet for communicating with one of the traps to be tested for the materials of interest and an outlet communicating with the detector inlet, the desorber including a manifold communicating with the inlet to the desorber for directing air from the manifold and across the inlet to the desorber, a heater for heating the desorber to evaporate any of the materials of interest on the trap, a pump for carrying the materials of interest on the air and into the detector; and a dryer assembly for drying air directed into the desorber, the dryer assembly comprising at least first and second dryers and at least one valve for selectively placing one of the first and second dryers in communication with the desorber while substantially isolating the other of the first and second dryers from the desorber. view more

The apparatus of claim 12, further comprising first and second heaters in proximity to the respective first and second dryers and being selectively operable for recharging the dryers.

The apparatus of claim 13, wherein the detector is an ion mobility spectrometer.

The apparatus of claim 13, further comprising a timer connected to the valve for alternately placing the first and second dryers in communication with the detector after a selected time.

A method for continuously operating a detector for detecting particles of interest, said method comprising:</claim-text> operating one of first and second dryers for defining an operated dryer and a non-operated dryer; directing a stream of air gh the operated dryer for transferring moisture from the stream of air to the operated dryer to produce a stream of dry air; directing the stream of dry air from the operated dryer toward an object to be tested for particles of interest and then toward the detector; recharging the non-operated dryer; and switching the stream of air from one of the dryers to the other after the non-operated dryer has been at least partially recharged and before the operated dryer has become saturated. view more

The method of claim 20, wherein the switching step is carried out after passage of a selected period of time.

The method of claim 20, wherein the re-charging step comprises heating the non-operated dryer to a temperature of at least 100° C.