Table 3.
Tentative assignments and m/z ratios for peaks in negative ToF‐SIMS spectra of melanin and microstructures in the Libros frogs
| Tentative assignment | Theoretical mass (u) | Melanin standard | Fossil frog | Sediment |
|---|---|---|---|---|
| C4 | 48.00 | 48.00 | 48.00 | 47.98 |
| C4H | 49.01 | 49.01 | 49.02 | 49.00 |
| C3N | 50.00 | 50.00 | 50.03 | 50.00 |
| C3HN | 51.01 | 51.01 | 51.03 | 51.02 |
| C3H2N | 52.02 | 52.02 | 52.02 | 52.01 |
| C5 | 60.00 | 60.00 | 60.01 | 59.99 |
| C5H | 61.01 | 61.01 | 61.00 | 61.00 |
| C4N/C5H2 | 62.00/62.02 | 62.01 | 62.02 | 62.00 |
| C4HN | 63.01 | 63.01 | 63.02 | 63.00 |
| C4H2N/CH4O3 | 64.02/64.02 | 64.01 | 63.98 | 63.96 |
| C4HO/H3NO3 | 65.00/65.01 | 65.01 | 65.02 | 65.00 |
| C3NO | 66.00 | 66.00 | 66.02 | 65.99 |
| C6 | 72.00 | 72.00 | 72.00 | 72.00 |
| C6H/C2H3NO2 | 73.01/73.02 | 73.01 | 73.02 | 73.01 |
| C5N/C2H2O3 | 74.00/74.00 | 74.00 | 74.02 | 74.01 |
| SO3 | 79.96 | 79.98 | 79.97 | 79.96 |
| HSO3 | 80.97 | 80.99 | 80.98 | 80.98 |
| C7 | 84.00 | 84.00 | 84.00 | 84.00 |
| C7H | 85.01 | 85.01 | 85.01 | 85.02 |
| C6N/C7H2 | 86.00/86.02 | 86.01 | 86.01 | 86.00 |
| C6HN | 87.01 | 87.01 | 87.02 | 87.02 |
| C6H2N/C3H4O3 | 88.02/88.02 | 88.02 | 88.02 | 87.99 |
| C6HO/C2H3NO3 | 89.00/89.01 | 89.01 | 89.02 | 88.99 |
| C5NO | 90.00 | 90.00 | 90.01 | 90.00 |
| C7H7 | 91.06 | 91.02 | 91.02 | 91.01 |
| C8 | 96.00 | 96.02 | 95.96 | 95.97 |
| HSO4/C4H3NO2 | 96.96/97.02 | 97.01 | 96.97 | 96.98 |
| C7N/C4H2O3 | 98.00/98.00 | 98.00 | 98.00 | 98.00 |
| C9 | 108.00 | 108.00 | 108.00 | 108.00 |
| C9H | 109.01 | 109.01 | 109.00 | 108.99 |
| C8N/C9H2 | 110.00/110.02 | 110.01 | 110.01 | 110.01 |
| C8HN | 111.01 | 111.01 | 111.02 | 111.02 |
| C8H2N/C5H4O3 | 112.02/112.02 | 112.02 | 112.00 | 111.98 |
| C8HO/C4H3NO3 | 113.00/113.01 | 113.02 | 112.99 | 112.99 |
| C7NO | 114.00 | 114.02 | 114.01 | 114.00 |
| C10 | 120.00 | 120.00 | 119.99 | 112.00 |
| C10H/C6H3NO2 | 121.01/121.02 | 121.01 | 121.00 | 120.98 |
| C9N | 122.00 | 122.00 | 121.99 | 121.98 |
| C12H/C8H3NO2 | 145.01/145.02 | 145.01 | 144.99 | 144.96 |
Grey shading highlights key N‐bearing molecular ions likely to be derived from melanin.