TABLE 1.
Mass isotopomer distribution of acetoin determined by GC/MSa
| Fragment | Mass isotopomer fraction | Mean mass isotopomer distribution ± SD |
||
|---|---|---|---|---|
| Theoretical | Unlabeled standard | Unlabeled sampleb | ||
| M-15 | m + 0 | 0.794 | 0.792 ± 0.000 | 0.791 ± 0.002 |
| m + 1 | 0.157 | 0.156 ± 0.000 | 0.157 ± 0.000 | |
| m + 2 | 0.044 | 0.044 ± 0.000 | 0.044 ± 0.000 | |
| m + 3 | 0.005 | 0.006 ± 0.000 | 0.006 ± 0.000 | |
| m + 4 | 0.000 | 0.003 ± 0.000 | 0.002 ± 0.002 | |
| M-43 | m + 0 | 0.811 | 0.806 ± 0.000 | 0.807 ± 0.000 |
| m + 1 | 0.142 | 0.150 ± 0.000 | 0.151 ± 0.000 | |
| m + 2 | 0.041 | 0.043 ± 0.000 | 0.042 ± 0.000 | |
a
The data comprise the means and standard deviations from duplicate measurements for standard and culture samples and theoretical values inferred from natural isotopic enrichment in nonlabeled substances (47).
b
Supernatant of A. pasteurianus NCC 316 grown in cocoa pulp simulation medium.