Table 2. . Intra-assay (six repeated analyses within one experiment during 20 h with samples stored in sample manager) and interassay validation.
| Compound | Linearity (R2) | LOD–LLOQ | % Matrix effects | Intra-assay (n = 6 during 20 h in +4°C) | Interassay (n = 3) | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Accuracy (% of target) | Precision (RSD%) | Accuracy (% of target) | Precision (RSD%) | ||||||||
| Conc A | Conc B | Conc A | Conc B | Conc A | Conc B | Conc A | Conc B | ||||
| TRP | 0.996 | 10.0–10.0 | -8.4 | 102 | 108 | 1 | 1 | 101 | 107 | 2 | 2 |
| L-KYN | 0.997 | 0.1–0.25 | -4.1 | 96 | 115 | 1 | 1 | 95 | 114 | 1 | 3 |
| KYNA | 0.998 | 0.1–0.5 | -12.1 | 102 | 106 | 1 | 1 | 102 | 106 | 2 | 1 |
| QUIN | 0.998 | 2.5–5.0 | 3.3 | 95 | 97 | 2 | 1 | 94 | 97 | 1 | 4 |
| PIC | 0.979 | 1.0–5.0 | 12.5 | 112 | 89 | 3 | 5 | 113 | 87 | 4 | 1 |
| NAA | 0.996 | 2.5–10 | 2.4 | 94 | 93 | 3 | 1 | 92 | 92 | 14 | 3 |
| NA | 0.997 | 1.0–5.0 | -4.0 | 101 | 96 | 9 | 1 | 97 | 95 | 2 | 1 |
| 3-HANA | 0.963 | 1.0–5.0 | -3.9 | 136 | 97 | 4 | 2 | 140 | 97 | 8 | 8 |
| XA | 0.989 | 2.5–10.0 | 6.0 | 95 | 85 | 2 | 2 | 97 | 86 | 7 | 3 |
| 3-HK | 0.997 | 0.25–1.0 | 23.4 | 94 | 91 | 1 | 2 | 95 | 92 | 1 | 2 |
Intra-assay (six repeated analyses within one experiment during 20 h with samples stored in sample manager) and interassay (three independent experiments within 2 days, all) validation results. Concentration A: two-times endogenous levels, B: ten-times endogenous CSF levels for all metabolites in blank CSF. Matrix effects calculated from ratio of IS area in matrix/IS are in blank sample). LOD–LLOQ concentration of TRP is in μM, all other metabolite (L-KYN, KYNA, QUIN, PIC, NAA, NA, 3-HANA, XA and 3-HK) concentrations are in nM.
3-HANA: 3-Hydroxyanthranilic acid; 3-HK: 3-Hydroxykynurenine; CSF: Cerebrospinal fluid; IS: Internal standard; KYNA: Kynurenic acid; L-KYN: L-Kynurenine; LLOQ: Lower limit of quantification (S/N ratio of ten); LOD: Limit of detection (S/N ratio of three); NA: Nicotinic acid; NAA: Nicotine amide; PIC: Picolinic acid; QUIN: Quinolinic acid; RSD: Relative standard deviation; TRP: Tryptophan; XA: Xanthurenic acid.