Backpropagation analysis for all 13 functional groups was performed to identify the regions of the spectra responsible for the result given. These plots are listed above in order of decreasing F1 score for the optimized IR+MS model. ) showing that the addition of new additional functional groups does not have a significant impact on the previous functional groups. The line plot in (c) shows that the accuracy only decreases for the redefined functional group. The plot of molecular perfection rate in (d) compares the performance of the machine learning model to a synthetic model to show that the decrease in molecular perfection rate is expected as the number of functional groups increases.