Table 1. Most abundant isotope of the repeating unit for FRPC computed by three methods and examples of accurate mass measurements with assignments of the sum of the masses of the end-groups for the first FRPC congener.
| R (most abundant isotope) | Assignment | Error (ppm) | |
|---|---|---|---|
| Mass difference between consecutive oligomers (maxima of isotopic pattern) | 569.7340 | 569.73236 ↓ C16H10O3Br4* |
+2.8 |
| Single rotation of Kendrick plot | 569.7293* or ** | −5.5 | |
| Double rotation of Kendrick plot | 569.7414** | +15.8 | |
| Example of accurate measurement, 1-mer | Assignment | Error (ppm) | |
| m/z measured | m/z theoretical* | ||
| 914.9116 | 914.9143 | C37H36Br4O6Na+ ↓ C16H10O3Br4+C21H26O3+Na+ (H, O, C and Br isotopes) |
−3.0 |
| 915.9117 | 915.9177 | −6.6 | |
| 916.9088 | 916.9125 | −4.0 | |
| 917.9100 | 917.9157 | −6.3 | |
| 918.9082 | 918.9107 | −2.8 | |
| 919.9104 | 919.9138 | −3.7 | |
| 920.9062 | 920.9093 | −3.3 | |
| 921.9096 | 921.9120 | −2.6 | |
| 922.9065 | 922.9086 | −2.3 | |
| 923.9074 | 923.9106 | −3.5 | |
| 924.9089 | 924.9132 | −4.7 | |
*using Mass Mountaineer, **using Kendo, first and twelfth horizontal alignments