CHNOPS elements detected in the CM of MC4, including the isotopes ¹H, ¹²C, ¹³C, ¹⁴N, ¹⁷O, ¹⁸O, ³¹P, ³²S, ³³S, and ³⁴S. The red line indicates the theoretical isotope mass, while the transparent blue box corresponds to a mass accuracy of ±30 ppm. Peak species are annotated, highlighting the high mass-resolving powers of LMS-GT. The isotopes ²H and ¹⁵N are below the noise floor. Mass lines around m/z = 16, including ¹⁶O, were blanked using the HV pulser of LMS-GT. ¹⁸O falls within a range with dominant electronic noise introduced by the HV pulser.