Gas Chromatography by Direct Aqueous Injection in Environmental Analysis
Environment: Water and Waste
Published Online: 15 SEP 2006
Copyright © 2000 John Wiley & Sons, Ltd. All rights reserved.
Encyclopedia of Analytical Chemistry
How to Cite
Biziuk, M. 2006. Gas Chromatography by Direct Aqueous Injection in Environmental Analysis. Encyclopedia of Analytical Chemistry.
- Published Online: 15 SEP 2006
Sample pretreatment, the initial stages of an analytical procedure, becomes the essential stage in environmental analysis. The only method of determination of organic compounds in water which avoids the isolation and preconcentration step uses direct injection of an aqueous sample on to a gas chromatographic column. Direct aqueous injection (DAI) is the simplest method for the determination of organic water pollutants. This method is also very fast and easy to automate. The method avoids the problems associated with using solvents (toxic and expensive) and incomplete recovery of the analytes during their isolation from the aqueous phase, the effect of potential contaminants when using solvent or solid-phase extraction (SPE), and losses of the analytes during the enrichment step.
The idea of DAI on to a chromatographic column is very old and for liquid chromatography and ion chromatography was widely applied from the beginning of these techniques. In the beginning of the application of this technique in gas chromatography (GC), packed columns were used. The real issue for the development of GC and the application of DAI is connected with introducing to practical use a capillary column with a polar or non-polar stationary thin liquid film or thin layer. The next, very important step was to introduce a direct injection on-column, which eliminates a lot of problems connected with injection in the split or splitless mode.
The determination of haloforms in water using DAI on to a capillary column and electron capture detection (ECD) was the most spectacular application of this method. The DAI/GC/ECD method was used for determination of haloorganic compounds in the different aqueous samples (tap, surface, swimming pool, and seawaters, beers, juices, soft drinks, and physiological liquids). This method was also used for the determination of semivolatile and nonvolatile haloorganic and other organic compounds in the different aqueous samples.