Pattern Recognition Studies of Halogenated Organic Compounds Using Conducting Polymer Sensor Arrays

Direct measurement of volatile and semivolatile halogenated organic compounds of environmental interest was carried out using arrays of conducting polymer sensors. Mathematical expressions of the sensor arrays using microscopic polymer network model is described. A classical, nonparametric, and unsupervised technique of cluster analysis was used to discriminate between polychlorinated organic phenol vapor response vectors in 2-dimensional space and to identify clusters or groups to which unknown vectors are likely to belong. The characteristic pattern for each sample was used to generate the database employed in the determination of the Euclidean distances between two given patterns and the normalized sensor response, as well as to develop a 2-dimensional mapping from a multidimensional space for quantifying the distinction of the samples. Results obtained demonstrated that conducting polymer sensor arrays can be utilized in the identification and quantitation of chlorinated organic phenols based on the differences in their Euclidean distances. The systematic differences, qualitatively defined by the Euclidean difference measurements, were most clearly visible when the nature and the function of the functional groups were considered.