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In this work, first and second dimensional retention index ( 1 I and 2 I) based calculation approach is established to simulate peak retention times ( 1 t R and 2 t R ) of samples for the given sets of volatile compounds in comprehensive two-dimensional gas chromatography-mass spectrometry (GC×GC-MS). For the result without 1 t R and 2 t R data of alkane references ( 1 t R(n) and 2 t R(n) ), the following steps were applied: (1) curve fitting based on van den Dool and Kratz relationship in order to simulate 1 t R(n) using a training set of volatile compounds in a sample with their experimental 1 t R data, and (2) simulation of 2 t R(n) at different 1 t R(n) to construct their isovolatility curves based on a nonlinear equation with p 1 -p 5 parameters and a constant (within the ranges of -0.0052 to 0.0049, -0.6181 to -0.0230, -26.4775 to -0.2698, 0.0050 to 9.6259, -7.2976 to -3.9524 and 0.9157 to 4.0779, respectively). These parameters were obtained by performing curve fitting according to the experimental 2 t R data of the same training set with the least square values ranging from 4.58×10 -15 to 32.55. Simulation of 1 t R and 2 t R of target analytes ( 1 t R,sim and 2 t R,sim ) with known 1 I and 2 I were performed using 1 t R(n) and the simulated isovolatility curves. All the calculations and curve fittings were carried out by using Solver in Microsoft Excel. The approach was applied to simulate results for 542 compounds in several samples including analysis of saffron (Crocus sativas L.), Boswellia papyrifera, acacia honey and incense powder/smoke, perfume and cannabis either reported from literature or from the experiments in this work using different experimental approaches. These were compared with the experimental data showing correlation with the R 2 ranges of 0.98-1.00 and 0.80-0.97 for 1 t R and 2 t R , respectively. This approach was then applied to propose 6 compounds which may be incorrectly identified based on the differences of >2 times of the standard deviations between 2 t R,sim and the experimental 2 t R in both residue and leave-one-out analyses., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Approaches to simulate peak time and intensity profiles of compounds in comprehensive two dimensional gas chromatography (GC × GC) were developed, and which are demonstrated for separation of a mixture of saturated and unsaturated fatty acid methyl esters (FAME) using a range of column sets. The simulation of first and second dimension time ( 1 t R and 2 t R ) of FAME relies on use of a Gibbs energy additivity approach to correlate with the structures of FAME. First and second dimension peak standard deviations ( 1 σ and 2 σ) of the compounds were further calculated from the 1 t R and 2 t R data according to the plate height concept which provided good agreement between the predicted and experimental peak widths at half height in one dimension GC (1DGC) with an overall R 2 of 0.9628. The effect of 1 σ distortion caused by the modulation process was also taken into account in the peak width simulation where the simulated 1 σ data were rounded up to multiples of the scale of modulation period (P M ). Two dimension Gaussian equations were then used to generate GC × GC results (2D contour plots) from simulated 1 t R , 2 t R , 1 σ and 2 σ data for FAME separation on different column sets employing ionic liquid and conventional columns. Good overall correlations between experimental and simulated 1 t R and 2 t R were obtained with R 2 of 0.9951 and 0.9802, respectively, and the simulated 2D contour plots were an acceptable match with the experimental results., (Copyright © 2019 Elsevier B.V. All rights reserved.)