Table I. Isotope contributions of amino acids.
| Amino acids | Q ion formula | 14N Q ion | 15N Q ion | 15N Q ion 2 | Isotope contribution (%) | Isotope contribution 2 (%) |
|---|---|---|---|---|---|---|
| Aspartic acid | C18H40NO4Si3 | 418 | 419 | 0.363 | ||
| Alanine | C14H32NO2Si2 | 302 | 303 | 0.266 | ||
| Valine | C13H30NO2Si2 | 288 | 289 | 0.255 | ||
| Leucine | C14H32NO2Si2 | 302 | 303 | 0.266 | ||
| Isoleucine | C14H32NO2Si2 | 302 | 303 | 0.266 | ||
| Glycine | C10H24NO2Si2 | 246 | 247 | 0.221 | ||
| Methionine | C13H30NO2SSi2 | 320 | 321 | 0.255 | ||
| Serine | C20H46NO3Si3 | 432 | 433 | 0.386 | ||
| Proline | C19H24NO4 | 330 | 331 | 0.22 | ||
| Threonine | C18H42NO3Si3 | 404 | 405 | 0.363 | ||
| Cysteine | C17H40NO2SSi3 | 406 | 407 | 0.359 | ||
| Phenylalanine | C17H30NO2Si2 | 336 | 337 | 0.299 | ||
| Glutamic acid | C22H48NO4Si3 | 432 | 433 | 0.409 | ||
| Glutamine | C19H43N2O3Si3 | 431 | 432 | 433 | 0.378 | 0.173 |
| Asparagine | C18H41N2O3Si3 | 417 | 418 | 419 | 0.367 | 0.149 |