Cocaine detection using surface acoustic wave immunoassay sensors

Vapor sensors, a.k.a. electronic noses, are becoming an increasingly popular analytical tool for detection and identification of small molecules in the gas phase. In this paper we present the results of a series of experiments demonstrating real-time vapor phase detection of cocaine molecules. A distinctive response or signature was observed under laboratory conditions, where the cocaine vapors were presented using an INEL vapor generator and under "field" conditions facilitated by the Georgia Bureau of Investigation (GBI) Crime Lab. For these experiments the sensor component was an ST-quartz resonator with a center frequency of approximately 250 MHz. Anti-benzoylegonine (anti-BZE) antibodies are attached to the electrodes on the device surface via a protein-A cross linker. We observed a large transient frequency shift accompanied by baseline shift with the anti-BZE coated sensor. After repeated experiments and the use of numerous controls we believe that we have achieved real time molecular recognition of cocaine molecules.