PERFORMANCE AND CHARACTERISTICS OF A TRACE GAS ANALYZER FOR THE DETERMINATION OF VOLATILE ORGANIC-COMPOUNDS IN AIR

An instrument has been developed and tested for the continuous measure ment of volatile organic compounds (VOC) in air, The system consists o f a gas chromatograph equipped with a dedicated sampling device that a llows the sample to be transferred to a cooled microtrap via sampling loops (10, 100, 250 ml) or via a direct pump transfer to the trap, The microtrap is placed in the chromatographic oven just below a modified split-splitless injector, allowing direct liquid injection for calibr ation of the system; the injector is in communication with the samplin g valve equipped with the loop and the sampling pump. The system allow s 24-hour sampling and analysis of a large number of VOC (up to 25 ind ividual hydrocarbons ranging from C2-C9) and also polar volatile organ ic compounds PVOC. Thanks to the particular trap geometry, a minimum c onsumption of liquid nitrogen (between 150-300 ml) is needed for each analytical run and no water managing system is normally required for h umid air samples.