Behavior of haloperidol and various phenothiazines on several alkyl bonded phases

Haloperidol and phenothiazines are present in psychiatrical treatments. An analysis in body fluids is tedious because of the presence of demethylated (DM) derivatives of phenothiazines. The behavior of some interfering solutes on alkyl bonded phases has been studied. Phenothiazines and DM derivatives exhibit a very similar behavior with a binary eluent (phosphate buffer-acetonitrile), which precludes an optimization with this system. When a ternary phase is used (phosphate buffer-acetonitrile-methanol), haloperidol and reduced haloperidol behave differently as compared with phenothiazines. In this mode it is possible to unambiguously detect haloperidol that would otherwise interfere. Phenothiazine peaks are characterized by a large tailing. An interesting feature is the comparison between cyclohexyl bonded and octadecyl bonded phases, the former being much more efficient.