Carbon NP oxidation has been studied extensively using ensemble methods such as flow tube reactors or flames. These methods have a number of major advantages, such as much higher experimental throughput, the ability to collect product NPs for post-reaction imaging or other analysis, and the ability to measure time scales ranging from hundreds of microseconds to a few seconds. The single NP approach used here is slow and limited, however, it allows several different effects of NP heterogeneity to be observed, that are averaged out in ensemble methods. We can measure the differences in reactivity between different individual NPs, but as illustrated in this study, we can also follow evolution of individual NPs as their etching rates fluctuate dramatically, eventually dropping to near zero. Single NP mass spectrometry, thus, provides a unique tool for examining structural evolution of carbon nanomaterials at high temperatures.