Modeling of the first dimensional peak with two modulated sub-peaks in comprehensive two-dimensional gas chromatography.

According to previous published works, precise modeling of the first dimensional (1D) peak in comprehensive two-dimensional gas chromatography (GC × GC) requires at least 3 modulated sub-peaks (MSP). This requirement is sometimes difficult to meet, e.g., in case of undersampling modulation. In the present work, the feasibility of modeling of the 1D peak with only 2 MSP was demonstrated. The effects of modulation phase (ϕ), modulation period (PM), the peak width (1σ), and the peak shape of the original 1D peak on the accuracy of the proposed method were explored. When employing PM ranging from 6 s ~ 3 s to modulate original peaks with 1σ = 1.2 s ~ 0.6 s, the maximal error of the modeled 1tR is 1.08 s, which is far less than the error generated by employing the largest MSP to estimate the 1tR. The deviation of modeled 1tR increases with the increase of peak shape distortion, and this deviation is ≤ 0.67 s when tailing factor (Tf) in the range of 0.8 to 1.5. The application of the proposed method was demonstrated by assisting identification of a monoterpene in Myrrh sample. The proposed approach could improve the accuracy in calculation of 1tR or 1I and enhance the reliability of compound identification in GC × GC analysis with undersampling modulation.