Development of a portable organic vapour analyser using quartz crystal piezoelectric sorption detector for monitoring of total organic compounds in air

Abstract

To solve the problem of high humidity interfering with the monitoring of organic vapours commonly found in workplace air using the piezoelectric crystal detector, a battery operated fan dryer was incorporated with the P/Z detector to provide a light, sensitive and portable monitor for analysing organic vapours in air. The organic vapour monitor developed is sensitive to analyse organic vapours at ppm levels below the control limits of these vapours. To select a suitable coating for the P/Z crystal detector to be used for diurnal monitoring of organic compounds in indoor air and in factories, eight gas-liquid chromatography coatings was chosen for study. Based on their sensitivity, selectivity, bleeding rate and long term stability towards commonly encountered organic vapours such as 1,1,1-trichloroethane, chloroform, benzene and toluene, Apeizon grease L was selected as the coating of the P/Z crystal. The optimised analytical parameters are : temperature 22°C-43°C, relative humidity 40%-100%, response time 2-30 minutes and linear working ranges 88.8ppm-1880ppm.