Computer-assisted analysis of gas chromatograph dataDr Ben Raymond and Paul Harvey, Australian Antarctic Division |
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| Abandoned fuel drums frozen into the snow at the main Wilkes' tip site, near Casey. Photographer: Paul Goldsworthy |
Project background
The Australian Antarctic Division's Human Impacts program is working to understand and manage contaminated sites in Antarctica. Gas chromatography is one of the analytical techniques used - particularly to assess fuel spills. Gas chromatography can indicate the type of product that has been spilled, along with information regarding the state of remediation of the site (e.g. to what extent evaporation or biodegradation is occurring).
We have developed a set of tools to assist with the analysis of gas chromatograph data. These tools provide computer-assisted methods for estimating the unresolved complex mixture (the "baseline") as well as characterising the peaks within the trace.
Progess
Estimation of the unresolved complex mixture (UCM)We use a linear combination of Gaussian functions to build a smooth approximation to the gas chromatograph trace. The problem is approached as a linear programming (optimisation) problem -- maximise the area under the smooth curve, without exceeding the sample values at any point. The width of the Gaussians determines the smoothness of the resulting curve: broader Gaussians yield a smoother curve. By varying the width parameter we can obtain a range of likely UCM curves, giving us (approximate) upper and lower bounds on the UCM.
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| Estimation of unresolved complex mixture. Diagram: Ben Raymond |
These tools are in an ongoing process of development. Contact for further information.
