Abstract
We have successfully determined the levels of acetylcholine (ACh) in seven rat brain regions by LC/MS equipped with direct sample introduction with splitting capability and a frit-fast atom bombardment (FRIT-FAB) ionization source system. Base peaks of the molecular ions of m/z 146 for ACh and m/z 150 for ACh-d4, the internal standard, were exhibited in the FRIT-FAB spectra with a small amount of fragments. Without requiring additional sample preparation or derivatization, the direct simultaneous determination of these ions by mass chromatography allowed detection of ACh levels as low as 1.0 pmol. The ACh levels measured by this approach were compared with those measured by conventional pyrolysis-GC/MS and LCEC. The similar ACh levels in the individual regions and their order were in accord with those determined by these three methods.
