While the HPLC characteriza=on of release dynamics hinged on fluorescence chromatograms, the mass data we collected in parallel (LCMS) also enabled tracking of the non-fluorescent elimina=on products. Working with DMT (10), we observed the classic post-release species with the expected m/z value, but also an unexpected second product with an m/z 2 Da lower (Fig. ). Intrigued by this unknown compound, we directed our aben=on to characterizing the molecular events driving iTCO-release. Given the higher reagent quan==es needed for isola=on and characteriza=on, we used iTCO-PEG4 ( ) and DMT (10) for a scaled-up reac=on, conducted at pH 7.4 for 24 h and then extended by another 48 h under an oxygen atmosphere to facilitate aroma=za=on. AUer 72 h, LCMS indicated a plateau in conversion, yielding a near-equimolar mixture of the expected aroma=za=on product Pa and the unknown species, matching our earlier observa=ons. Chromatographic separa=on of this mixture and subsequent NMR analysis confirmed the structure of the aroma=za=on product Pa. Unexpectedly, the second compound was iden=fied as the aroma=zed cyclic ether Pia (Fig. ).