An inverted phase (polar to non-polar) column set has been compared with a non-polar to polar column set for the GC x GC separation of petroleum hydrocarbons. This column configuration is shown to provide greatly enhanced resolution for less polar compounds and makes greater use of the two dimensional separation space. It improves resolution of a greater number of components within one analysis and offers new possibilities for crude oil fingerprinting.
Tran, T., Logan, G., Grosjean, E., Harynuk, J., Ryan, D., & Marriott, P. (2006). Comparison of column phase configurations for comprehensive two dimensional gas chromatographic analysis of crude oil and bitumen. Organic Geochemistry, 37(9), 1190 - 1194. https://doi.org/10.1016/j.orggeochem.2006.05.006