Overall, similar trends were observed for all theoretical isotopologue distributions with EMD values ranging from -0.5 to 0.5 Da for all six elemental ratios. To evaluate this trend, the Pearson correlation coefficients between the EMD mono and EMD iso values were obtained. These coefficients were calculated separately for each elemental ratio and isotopologue mass depth of 1 till 6 (Table ). The highest correlation of 1.00 was found for the elemental ratio CN with an isotopologue mass depth of 1 and the lowest value was 0.86 for both the elemental ratios CCl and CS with an isotopologue mass depth of 5 (Figure and S4, respectively). Overall, the Pearson correlation coefficient decreases with a higher isotopologue mass depth except for an isotopologue mass depth of 6. It is expected that this was due to a relatively low number of mono-iso pairs with a depth of 6 (Table ). These results showed that similar EMD values for mono-iso pairs were obtained throughout the theoretical dataset.