We can use assumption (iv) to estimate the likelihood that the proposed molecular mass is correct. In particular, a set of estimated neutral loss masses associated with the query spectrum can be constructed with each entry of the set computed as the difference between 𝑚 " ! and all fragment ion masses in the spectrum. If 𝑚 " ! is the true molecular mass of the analyte, most estimated neutral losses should follow our expectations of logical neutral loss values. If 𝑚 " ! is not the true molecular mass of the analyte, some of the estimated neutral losses may be illogical. While there are some general rules about acceptable neutral losses, these often include more nuanced ideas such as isotopic envelopes that are difficult to generalize. Accordingly, we consider a data-driven first approximation of neutral loss logicality for ease of implementation. Further refining the algorithm to incorporate known rules and more sophisticated modeling is on-going work.