Mass fragmentographic determination of 5-hydroxytryptamine and 5-hydroxyindole-3-acetic acid in brain tissue using deuterated internal standards.

A mass fragmentographic method for the determination of 5-hydroxytryptamine (5-HT) and 5-hydroxyindole-3-acetic acid (5-HIAA) in the same extract of rat brain tissue is decribed. Deuterium-labelled analogues were used as internal standards. 5-HT and 5-HIAA were separated by solvent extraction and pentafluoropropionyl derivatives were prepared for the mass fragmentographic analysis. Multiple ion analysis confirmed the identity of 5-HT and 5-HIAA in the rat brain. At the mass numbers used routinely for the determination of 5-HT and 5-HIAA in the rat brain. At the mass numbers used routinely for the determination of 5-HT and 5-HIAA, the experimental error was below 3% (calculated from mean values of 0.05 and 0.24 nmole, respectively). The recovery of the authentic compounds added to brain extracts was more than 95%. The levels of 5-HT and 5-HIAA in the rat brain were 2.95 +/- 0.16 and 0.64 +/- 0.18 nmole/g, respectively. More than 100 samples could be analyzed within 3 days. The presence of 5-hydroxytryptophol in rat brain was also investigated, but none could be detected either as a conjugate or as the free alcohol.