Multicomponent gas analysis of a mixture of chloroform, octane and toluene using a piezoelectric quartz crystal sensor array Original Research Article

Piezoelectric devices with gold electrodes and AT-cut quartz crystals, coated with polydimethylsiloxane, polyether urethane, polyethylcellulose and polycyanopropylmethylsiloxane were used in an array of four piezoelectric quartz crystal sensors. The quartz crystals were fixed into a thermostated chamber equipped with inlet and outlet for gas permeation. The data acquisition and gas flow were PC controlled. The calibration for organic vapors was carried out by isothermal exposure at room temperature with concentrations ranging 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 prediction values were 86% and 107%, respectively; with toluene and octane mixtures the values were high for toluene and from 108% to 120% for octane; for octane and chloroform mixtures, high values were obtained for octane and 93–107% prediction was obtained for chloroform. For tertiary mixtures of the three organic compounds, prediction values of 93–106% for octane and 92–93% for chloroform, while for toluene somewhat low values, 72–108%, were obtained.