CROWN ETHER-COATED PIEZOELECTRIC CRYSTAL SENSOR ARRAY FOR DETECTION OF ORGANIC VAPOR MIXTURES USING SEVERAL CHEMOMETRIC METHODS

An array of nine piezoelectric quartz crystal sensors, each coated wit h a different crown ether derivative, was constructed for multicompone nt analysis of organic vapors, The usefulness of this array was evalua ted by quantifying known mixture samples in two three- and one four-co mponent cases; the first sample set consisted of aniline, butan-1-ol a nd acetonitrile, the second of pyridine, pyrrole and tetrahydrofuran a nd the third of formic acid, acetic acid, propionic acid and acrylic a cid, Three chemometric techniques, viz, artificial neural networks (AN N), partial least squares (PLS) and non-linear partial least squares ( NPLS), mere used in the data analysis, The results showed that better prediction was achieved with ANN in all cases, Also, as the number of components present in the mixture increased, the sensors tended to exh ibit non-linear sensory behavior, The effect of the number of neurons in the hidden layer on the performance of the network is also discusse d.