This document describes a new HPLC method for the determination of the tricyclic antidepressant doxepin in 'Aponal 100' tablets. The method uses an extra densely bonded Eclipse XDB-C18 column, which is made with a special Zorbax silica support and designed to reduce or eliminate strong adsorption of basic or acidic compounds. The method is stable at neutral pH and shows excellent and rapid resolution of tricyclic aromatic amines at low buffer concentration. Doxepin is separated from 'Aponal 100' tablets with no interference from excipients.
This document details the high-performance liquid chromatography (HPLC) analysis of the tricyclic antidepressant doxepin in 'Aponal 100' tablets. The method utilizes an Agilent 1100 Series HPLC system equipped with a Zorbax Eclipse XDB-C18 column to achieve excellent peak shape and rapid resolution of tricyclic aromatic amines at neutral pH. The analysis successfully separates doxepin from excipients and other tricyclic antidepressants like imipramine and amitriptyline.
| Equipment | Agilent 1100 Series HPLC |
|---|---|
| Mobile Phase A | 0.025 M KH2PO4 in water (pH = 7) |
| Mobile Phase B | Methanol |
| Temperature | 25 °C |
| Flow Rate | 1.0 mL/min |
| UV Detector Wavelength | 210 nm |
Yes, doxepin is stable at neutral pH, which is the condition used in this method.
The autosampler temperature must be set to 4 °C to avoid sample decomposition.
The analysis is performed with a flow rate of 1.0 mL/min.