Multicomponent gas analysis of a mixture of chloroform, octane and tolueneusing a piezoelectric quartz crystal sensor array

Piezoelectric devices with gold electrodes and AT-cut quartz crystals, coat ed with polydimethylsiloxane, polyether urethane, polyethylcellulose and po lycyanopropylmethylsiloxane were used in an array of four piezoelectric qua rtz crystal sensors. The quartz crystals were fixed into a thermostated cha mber equipped with inlet and outlet for gas permeation. The data acquisitio n and gas flow were PC controlled. The calibration for organic vapors was c arried out by isothermal exposure at room temperature with concentrations r anging from 100 to 1000 ppm for toluene and chloroform and from 250 to 2000 ppm for n-octane. In binary mixtures of toluene and chloroform the predict ion values were 86% and 107%, respectively; with toluene and octane mixture s the values were high for toluene and from 108% to 120% for octane; for oc tane and chloroform mixtures, high values were obtained for octane and 93-1 07% prediction was obtained for chloroform. For tertiary mixtures of the th ree organic compounds, prediction values of 93-106% for octane and 92-93% f or chloroform, while for toluene somewhat low values, 72-108%, were obtaine d. (C) 1999 Elsevier Science B.V. All rights reserved.