Table 1.
Quantification results for the nitrogen heterocyclic molecules targeted in the present study
| Name of molecule | Molecular formula | Molecular structure | Mass-to-charge ratio (m/z) of the protonated ion | Yield (ppm)a by a C18 column | Yield (ppm)a by a HypercarbTM column |
|---|---|---|---|---|---|
| Nucleobases | |||||
| Cytosine | C4H5N3O | (1) | 112.0505 | 2 | 1 |
| Uracil | C4H4N2O2 | (2) | 113.0346 | 1 | 4 |
| Thymine | C5H6N2O2 | (3) | 127.0502 | 2 | <3 |
| Adenine | C5H5N5 | (4) | 136.0618 | 0.1 | — |
| Hypoxanthine | C5H4N4O | (5) | 137.0458 | 0.06 | 0.2 |
| Guanine | C5H5N5O | (6) | 152.0567 | — | — |
| Xanthine | C5H4N4O2 | (7) | 153.0407 | 0.04 | — |
| Nitrogen heterocycles | |||||
| Pyridazine | C4H4N2 | (8) | 81.0447 | 19 | 31 |
| Pyrimidine | C4H4N2 | (9) | 81.0447 | <1 | <1 |
| Pyrazine | C4H4N2 | (10) | 81.0447 | 35 | 41 |
| Purine | C5H4N4 | (11) | 121.0509 | 2 | 5 |
| Imidazole | C3H4N2 | (12) | 69.0447 | 1152 | 1163 |
| Pyrazole | C3H4N2 | (13) | 69.0447 | 89 | 20 |
| 4-Imidazolcarboxylic acid | C4H4N2O2 | (14) | 113.0346 | b | 139 |
| Glycine anhydride | C4H6N2O2 | (15) | 115.0502 | 3 | 42 |
| Dihydrouracil | C4H6N2O2 | (16) | 115.0502 | <1 | 61 |
For backing up the quantitative evaluation of those N-containing target molecules, we conducted the two independent chromatographic separations and co-injection determination with the corresponding authentic standard reagent (Supplementary Note 1). The small scale detection and calibration lines of the orbitrap mass spectrometry were also validated as shown in Supplementary Fig. 35
aRelative weight with relevance to the total deposited gas in part per million (1 ppm = 0.0001%) normalised with each carbon abundance
bPositively identified but not quantified