Naive Bayes classification was used to develop a probabilistic isotopologue detection model, using the TP and TN dEMD probability distributions obtained for the selected elemental ratios (i.e. CO, CCl, CN, CS, CF, and CH). To calculate the posterior probabilities (i.e., P(A|B)) for classifying a potential mono-iso pair as TP or TN, Bayes theorem is used (Equation 4). Here, P(A) is the probability of an mono-iso pair being TP or TN, P(B) is the occurrence likelihood for a specific dEMD value, P(B|A) is the probability for a dEMD value in case of A, and n equals the number of elemental ratios used, which would be six for our model (i.e., CO, CN, CCl, CS, CF, and CH).