Rapid extraction high-speed GC analysis of volatile organic compounds in aqueous samples

An extraction system to remove volatile organic compounds (VOCs) from an aq ueous matrix in a time frame that is compatible with high-speed gas chromat ography (HSGC) has been developed and interfaced to a cryofocusing instrume nt. Using this system, VOCs are quantitatively extracted in similar to 20 s , with no residual signal present during subsequent analysis. This allows s uccessive injections, as demonstrated by sequential extraction and separati on of four aqueous samples in less than 31/2 min. Analysis time was minimiz ed by designing the system to allow concurrent extraction and separation. T he entire sample extract is introduced to the cryofocusing injector of the HSGC, resulting in excellent sensitivity. Injection of only 100 mu L of an aqueous mixture of VOCs in the low parts per billion range resulted in chro matographic peaks with signal-to-noise ratios ranging from 6.5 to 41 depend ing on analyte. Reproducibility of sequential analyses at this concentratio n resulted in less than 5% relative standard deviation.