Membrane/gas chromatographic system for automated extraction and determination of trace organics in aqueous samples

A new automated extraction analysis system, which combines membrane cell technology with a pneumatically operated pressurized rotary gas chromatographic injection valve (PO-PSI), was developed and tested. The system was evaluated by using chlorinated aromatic compounds and pesticides as test sample mixtures. These compounds were successfully extracted and determined in water and organic/water type matrices in the part-per-trillion to part-per-billion range. Two modes of membrane operation were demonstrated: the continuous-flow mode, which produces concentration factors of similar to 3-5, and the stop-flow mode, which produces concentration factors of similar to 50-200. The effects of adding common organic solvents to the samples were examined and unexpected increases in extraction efficiency were observed.