Vapor sensing instruments for ultra trace chemical detection

A detector for detecting an analyte, comprising:

• a housing defining an enclosed sensing volume adapted to pass a carrier and having an adsorption/desorption zone, the housing having an inlet and an outlet communicating with the enclosed sensing volume such that a carrier gas can be moved sequentially through the inlet, the enclosed sensing volume and the outlet;
• means for effecting selective adsorption/desorption of at least a portion of the molecules of the analyte in the adsorption/desorption zone of the housing;
• a sensing assembly for sensing the analyte delivered by the carrier, the sensing assembly being downstream from the adsorption/desorption zone whereby the carrier passes through the adsorption/desorption zone prior to delivering the analyte to the sensing assembly, the sensing assembly comprising:
• a sensing unit constructed of an amplifying fluorescent polymer, the intensity of light generated by the amplifying fluorescent polymer varying in response to interaction of the amplifying fluorescent polymer with molecules of the analyte delivered by the carrier;
• a source of excitation producing a medium that interacts with the amplifying fluorescent polymer to cause the amplifying fluorescent polymer to generate light;
• a light detector positioned to receive light generated by the amplifying fluorescent polymer, the light detector outputting a signal indicative of the intensity of the light generated by the amplifying fluorescent polymer;
• and
• a converter assembly indicating the presence of the analyte delivered by the carrier after receiving a timing signal indicative of the initiation of desorption of the molecules of the analyte from the adsorption/desorption zone and the signal from the light detector indicating a change in intensity of the light generated by the amplifying fluorescent polymer of the sensing unit at a predetermined time period after the reception of the timing signal by the converter assembly.