Automatic Determination of Clomipramine, Imipramine and Their Demethylated Metabolites in Plasma by High Performance Liquid Chromatography

Abstract

Determination of tricyclic antidepressant drugs (clomipramine, imipramine and their demethylated metabolites) in plasma can be carried out by extraction on a precolumn (n-octyl bonded silica gel) and washing with phosphate buffer (0.005 M, pH = 11.5). The elution is carried out on-line (with back-flush) on an alkylnitrile bonded silica gel column with the mobile phase: acetonitrile-methanolphosphate buffer 0.005 M, pH = 7.2, 50: 25: 30 (v/v). The AASP (Advanced Automated Sample Processor) allows full automatization for this determination. The total analysis time is only 10 minutes. The obtained reproducibility is 5.6% for clomipramine and 4% for demethylclomipramine while the detection limit (10 μL⁻¹) is lower than the therapeutic concentrations of these antidepressants (and metabolites) in plasma. The correlation with the classical (but tedious) method involving liquid-liquid extraction is excellent.