Chlorpromazine metabolism IV: quaternization as a key to determination of picomoles of chlorpromazine and other tertiary amine drugs.

Reaction of chlorpromazine with 9-bromomethylacridine under appropriate conditions yields a nonfluorescent quaternary ammonium derivative which, on subsequent photolysis, liberates fluorescence. The major component of this fluorescence is 9-methylacridine (86%), while two minor components are 9-acridinecarboxaldehyde (6%) and 9-acridinemethanol (8%). The mechanism of photolysis leading to formation of these products appears to involve homolytic as well as heterolytic cleavages of the quaternary salt. Both the quaternization and the photolysis are stoichiometric. Appropriate isolation of the fluorescence and its quantitative determination constitutes the basis of a new and highly sensitive assay applicable to chlorpromazine and other tertiary amine drugs.