Within the measured subspace of the exposome chemical space, a large portion of the detected chemicals remain unidentified. This implies that a large portion of the collected analytical signals, even though of high quality, remain unidentified. An example of these cases is the mid-size chain PFAS chemicals in lipidomics studies, as both studies use very similar experimental setup. Recent studies have indicated that the retrospective analysis can be employed to further annotate/identify the unknowns in the archive datasets. The retrospective analysis of the archived data, even though it has shown a great potential, has not been widely applied for the exploration of the measured chemical space. This shortcoming mainly has been due to inadequate data processing tools, limited chemical and spectral databases, the hypothesis-driven approaches used in NTA experiments, and limited computational power available to different research groups.