DIRECT DETERMINATION OF ACETYLCHOLINE IN MOUSE BRAIN BY THERMOSPRAY-MASS SPECTROMETRY.

Measurement of tissue levels of acetylcholine and choline have long been employed as a means of characterizing the cholinergic nature of a system of interest. Early analyses were performed mainly by bioassay techniques such as those utilizing the clam heart, the dorsal muscle of the leech and the frog rectus abdominus. These obviously indirect and non-specific procedures were replaced in the early 1970's by GC and GC-MS methods which require removal of one of the quaternary methyl groups to provide a volatile product. This can be accomplished by chemical or thermal means. By the use of thermospray HPLC-mass spectrometry the analysis is performed on the intact acetylcholine or choline molecule with no derivatization or pre-treatment needed.