Table 3.
Recoveries (%) of the silyl derivatives of indolic acids from model solution (derivatization with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) or N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide (MTBSTFA)), pooled cerebrospinal fluid (CSF) samples and serum samples at three concentration levels using microextraction by packed sorbent (MEPS) as a sample preparation technique and BSTFA as a derivatizing reagent (n = 3, p = 0.95).
| Indolic Acid Derivative | Model Solution | Pooled CSF | Blood Serum | |||||
|---|---|---|---|---|---|---|---|---|
| BSTFA | MTBSTFA | 100 a | 500 b | 1500 c | 100 a | 500 b | 2000 d | |
| Indole-3-acetic acid (3IAA), mono- | 80 ± 20 | 80 ± 10 | 80 ± 20 | 80 ± 20 | 80 ± 10 | 60 ± 20 | 60 ± 10 | 60 ± 20 |
| Indole-3-carboxylic acid (3ICA), mono- | 70 ± 10 | 70 ± 20 | 60 ± 20 | 70 ± 20 | 60 ± 10 | 60 ± 10 | 70 ± 20 | 60 ± 10 |
| Indole-3-propionic acid (3IPA), mono- | 62 ± 6 | 40 ± 10 | 70 ± 20 | 70 ± 10 | 70 ± 10 | 48 ± 9 | 50 ± 10 | 50 ± 10 |
| Indole-3-lactic acid (3ILA), di- | 80 ± 20 | 70 ± 20 | 80 ± 20 | 70 ± 20 | 80 ± 20 | 50 ± 10 | 50 ± 10 | 60 ± 10 |
| 5-Hydroxyindole-3-acetic acid (5HIAA), di- | 52 ± 8 | 40 ± 10 | 40 ± 10 | 50 ± 10 | 50 ± 10 | 40 ± 10 | 38 ± 6 | 40 ± 10 |
a 100 µg/L corresponds to 0.4–0.5 µM; b 500 µg/L corresponds to 2.0–2.5 µM; c 1500 µg/L corresponds to 6–7 µM; d2000 µg/L corresponds to 8–10 µM.