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 (D) 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 D peak with only 2 MSP was demonstrated. The effects of modulation phase (ϕ), modulation period (P), the peak width (σ), and the peak shape of the original D peak on the accuracy of the proposed method were explored. When employing P ranging from 6 s ~ 3 s to modulate original peaks with σ = 1.2 s ~ 0.6 s, the maximal error of the modeled t is 1.08 s, which is far less than the error generated by employing the largest MSP to estimate the t. The deviation of modeled t increases with the increase of peak shape distortion, and this deviation is ≤ 0.67 s when tailing factor (T) 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 t or I and enhance the reliability of compound identification in GC × GC analysis with undersampling modulation.