Detection of organosulfur (CHNOS) compounds in S⁷⁺-over-irradiated residues: (a, b) ESI-FT-ICR mass spectra enabled the detection of organosulfur (CHNOS) compounds in S⁷⁺ -over-irradiated residues (2nd row, darkgray). The “CHNOS-only” spectrum (3rd row, red) illustrates 908 CHNOS-assigned m/z signals that were absent in the Ar⁷⁺-irradiated ice (reference sample, 1st row, lightgray); (c) Organosulfur (CHNOS) compounds have been validated by isotopic fine structure as exemplarily shown for the [C₂₂H₃₃N₄O₃S]⁻ molecular ion (darkgray = experimental spectrum, red = simulated isotopic pattern). Due to low intensities, (M-1)⁻ +2 and (M-1)⁻+3 isotopologues are mixed with the noise signal.