Table 2.
Spectroscopic and chromatographic properties of tryptophan and its major metabolites.
| Analyte | λmax of ex (nm) | λmax of em (nm) | λmax of abs (nm) | Extinction coefficient (dm3 mol−1 cm−1) | LOD (mol) | S/N | RT (min) |
|---|---|---|---|---|---|---|---|
| TRP | 297 | 348 | 220 | 2.94 × 104 | 5.36 × 10−12 | 2.19 | 30.8 |
| 280 | 7.82 × 103 | 4.89 × 10−14 | 2.13 | ||||
| 300sh | 6.45 × 103 | ||||||
| 5-HT | 297 | 348 | 220 | 3.25 × 104 | 5.84 × 10−12 | 2.55 | 7.91 |
| 280 | 5.51 × 103 | 1.13 × 10−13 | 2.06 | ||||
| 300sh | 4.68 × 103 | ||||||
| 5-HIAA | 297 | 348 | 220 | 2.65 × 104 | 6.64 × 10−12 | 2.45 | 17.6 |
| 280 | 6.36 × 103 | 8.25 × 10−14(fl) | 2.15 | ||||
| 300sh | 5.46 × 103 | ||||||
| KYN | 364 | 480 | 226 | 2.44 × 104 | 4.8 × 10−12 | 2.17 | 12.1 |
| 254 | 9.5 × 103 | 1.20 × 10−12 | 2.05 | ||||
| 364 | 5.05 × 103 | ||||||
| KYNA | 330 | 390 | 216 | 2.95 × 104 | 3.28 × 10−12 | 2.14 | 21.6 |
| 242 | 3.92 × 104 | 1.13 × 10−13 | 2.18 | ||||
| 330 | 6.79 × 103 | 2.24 |
TRP, tryptophan; 5-HT, serotonin; 5-HIAA, 5-hydroxyindoleacetic acid; KYN, kynurenine; KYNA, kynurenic acid; λmax of ex, wavelength of excitation maximum; λmax of em, wavelength of emission maximum; λmax of abs, wavelength of absorbance maximum; sh, shoulder; fl, by fluorescence; LOD, limit of detection represented in number of moles injected on the column observed for absorbance used for quantification of given analyte (top values) and fluorescence; S/N, signal-to-noise ratio; RT, retention time.