Table 2.
Retention times of amino acids–DPAA derivative from LCMS.
| AA Derivative | Neg/pos ESI Molecular Ion m/z’s | Rt of L-DPAA-AA of TA a | Rt of L-DPAA-AA of 1 | Rt of L-DPAA-AA of 2 | Rt of L-DPAA-AA of 3 | Rt of D-DPAA-AA of 3 | Rt of L-DPAA-AA of 4 | Rt of D-DPAA-AA of 4 |
|---|---|---|---|---|---|---|---|---|
| L-sHis-D-sAla b | 493/495 | 12.2 | 12.4 | 12.4 | 12.4 | 7.9 | 12.3 | 7.9 |
| L-sHis-D-sAla b | 493/495 | 13.1 | 13.3 | 13.1 | 13.4 | 11.6 | 13.3 | nd |
| L-Ser | 356/358 | 24.8 | 25.1 | 24.9 | 24.9 | 25.8 | 24.7 | 25.7 |
| L-iSer | 356/358 | 27.0 | 27.3 | 27.2 | 27.2 | 26.4 | 27.1 | 26.3 |
| L-alloThr | 370/372 | 27.1 | 27.3 | 27.2 | 27.2 | 30.0 | 27.1 | 30.1 |
| L-Asp | 384/386 | 28.7 | 29.1 | 28.7 | 28.9 | 31.8 | 28.8 | 31.9 |
| L-(2S,3R)-Has | 400/402 | 30.2 | 30.7 | 30.0 | 30.1 | 28.5 | nd | 28.8 |
| L-Aad | 412/414 | nd d | 33.8 | 33.8 | 33.7 | 37.3 | 33.7 | 37.4 |
| Apoa/Apcoa | 512/514 | nd | nd | nd | nd | nd | nd | nd |
| L-sHis-D-sAla c | 745/747 | 42.5 | 42.4 | 42.3 | 42.5 | 40.0 | 42.3 | 39.7 |
| L-Phe | 416/418 | 51.7 | 51.8 | 51.6 | 51.7 | 57.8 | 51.6 | 57.9 |
| (2S,3S)-MePhe | 430/432 | - | -- | -- | 56.1 | 62.0 | - | - |
| (2S,3S)-BrMePhe | 508,510/510,512 | 64.6 | 64.7 | 64.6 | - | - | 64.5 | 66.9 |
a Theonellamides A,D,E mixture. b The two isomeric mono-DPAA derivatives. c Di-DPAA derivative. d Not detected.