Vapor recognition with an integrated array of polymer-coated flexural plate wave sensors

Preliminary testing of a prototype instrument employing an integrated array of six polymer-coated flexural plate wave (FPW) sensors and an adsorbent p reconcentrator is described. Responses to thermally desorbed samples of ind ividual organic solvent vapors and binary and ternary vapor mixtures are li near with concentration, and mixture responses are equivalent to the sums o f the responses of the component vapors, which co-elute from the preconcent rator in most cases. Limits of detection as low as 0.3 ppm are achieved fro m a 60-s (34 cm(3)) air sample and peak widths at half-maximum range from 1 to 4 s. Tests at different flow rates suggest that the kinetics of vapor s orption in the sensor coating films may limit responses at higher flow rate s, however, low data acquisition rates may also be contributory. Assessment s of array performance using independent test data and Monte Carlo simulati ons with pattern recognition indicate that individual vapors and certain bi nary and ternary mixtures can be recognized/discriminated with very low err or. More complex mixtures, and those containing homologous vapors, are prob lematic. This is the first report demonstrating multi-vapor analysis with a n integrated FPW sensor array. (C) 2000 Elsevier Science S.A. All rights re served.