Screening method for the determination of 28 volatile organic compounds in indoor and outdoor air at environmental concentrations using dual-column capillary gas chromatography with tandem electron-capture-flame ionization detection

A gas chromatographic method is presented for the simultaneous determination of 28 volatile organic compounds (VOCs) in indoor and outdoor air at environmental concentrations. Using diffusive (passive) samplers, the VOCs were adsorbed onto charcoal during a four-week sampling period and subsequently desorbed with carbon disulphide. After injection, using a cold split-splitless injector, the mobile phase was split via a Y-connector and led onto two capillary columns of different polarity switched in parallel. This dual-column configuration provides additional information about the VOC components and can be obtained for verification purposes. Detection was in both cases performed by connecting each column with a non-destructive electron-capture detector and a flame ionization detector switched in series. By this procedure sensitivity is increased because no effluent splitting is required. At the same time, sample throughput is enhanced drastically since several items of information are obtained simultaneously. The procedure has been successfully applied in the context of a large field study to measure outdoor air concentrations in three areas with different traffic density. It is applicable to indoor air measurements in like manner.