Quantitative aspects in comprehensive two-dimensional gas chromatography

The effect of the amount of matrix compounds in comprehensive two-dimensional gas chromatographic (GC × GC) separation of polycyclic aromatic hydrocarbons (PAHs) was investigated. The second dimension column was overloaded by progressively increasing the matrix amount and the separation was evaluated by inspecting peak widths, asymmetries, resolution, retention times, peak areas and volumes of the target compounds. In quantitative analysis, two different calibration methods were tested for both raw sediment extracts and cleaned extracts, i.e. for extracts in which the matrix was removed by a liquid chromatographic clean-up step. The quality of the separation was not significantly disturbed in terms of peak width, asymmetry and resolution when the amount of matrix was increased. However, the depth of the valley between PAH and preceding matrix peak increased with an increase in matrix amount and the repeatabilities of retention times, peak areas and volumes decreased. In quantitative analysis, calibration by using areas had a tendency to underestimate the trace amounts of PAH, especially for the non-cleaned samples. In case of volume calibration, the most accurate results were obtained by external calibration for both cleaned and non-cleaned samples.