Resolve the origin of the weak C₃H₈NO signal at m/z 74

Determine whether the minor unaccounted-for signal at m/z 74 in the ROSINA DFMS spectrum of comet 67P/Churyumov-Gerasimenko is the molecular-ion-minus-hydrogen fragment of a C₃H₉NO parent species that lacks a significant molecular-ion signal.

Background

The authors identify a small residual signal at m/z 74, corresponding to C₃H₈NO, that could represent an M−H fragment from an as-yet-unidentified C₃H₉NO parent. The possible parent would need to produce little or no detectable molecular-ion signal, making it difficult to distinguish from instrumental noise or other overlapping contributions. Because the signal is close to the DFMS detection limit, the paper leaves its chemical interpretation unresolved.

References

A very minor but unaccounted for signal of C₃H₈NO on m/z = 74 might be an M-H fragment of a C₃H₉NO parent that does not yield a relevant M signal. However, this signal's intensity is close to the instrument's detection limit and no reliable statement can be made.

— Nitrogen- and nitrogen-oxygen-bearing organic molecules in comet 67P/Churyumov-Gerasimenko: An untargeted investigation  (2608.24235 - Hänni et al., 25 Aug 2026) in Section 4.1, “Unexplained intensity”