Leachable investigations are routinely undertaken across a range of sectors, including Electronic Nicotine Delivery Systems (ENDS), to determine if any chemicals from the container closure system can migrate or leach into a product. In general, leachable study conditions and analytical protocols are fairly straightforward, however, risk assessment of the analytical results can be challenging and may require additional data. Herein, we present a case study of the analytical investigation of two leachable compounds with little, if any, toxicological information (data deficient) that were found in simulated leachable studies using JUULpods filled with flavorless base formulation (PG/VG/nicotine/benzoic acid). Because no commercial reference standards for the two data deficient leachable compounds were available, nor any reasonable synthetic route possible due to the compounds’ molecular size and structural complexity, an analytical approach was needed to determine whether these two data deficient leachable compounds identified in aged e-liquid from JUULpods transfer to the aerosol. LC-MS/MS analysis using ESI negative mode confirmed that molecular mass and fragmentation patterns for each leachable compound in e-liquid were consistent with proposed structures and compound rationalizations reported in simulated leachable studies. Upon e-liquid confirmation, aerosol was collected from aged JUULpods in order to determine the transfer efficiency of leachable compounds from e-liquid to aerosol. Aerosol collected from aged JUULpods did not contain any detectable levels of either leachable compound, and transfer efficiency from e-liquid to aerosol was experimentally determined to be < 2%. The novel analytical approached used in this case study provided experimentally determined exposure estimates on two data deficient leachable compounds to support risk assessment and the observation that larger compounds have limited transfer efficiencies into the aerosol.