Retention time correction in gas chromatography by modeling concentration related effects, applied to the analysis of fatty acid methyl esters

•Concentration effects on the retention time have been studied for a polar GC-column.•Mathematical models for these effects have been drawn up.•The applicability of such models in fatty-acid-analysis is demonstrated.

Constant and reproducible retention times are a basic requirement to allow the automatic peak assignment in complex gas chromatograms. Drifting retention times are best handled by frequent updates, based on reference peaks. Some refinements of this concept have been reported as well as alternative concepts, including pattern recognition algorithms to achieve ultimate precision; however, in applications requiring a wide concentration range, the effects of concentration on the retention time of individual peaks may become relevant, requiring special considerations. The analysis of fatty acid methyl esters is such an application. A model describing concentration related effects was drawn up and found to work best for this purpose. The precision of peak alignment could be improved by an order of magnitude, allowing reliable automation of routine analysis.