Optimised procedures for the reversed-phase liquid chromatographic analysis of formulations containing tricyclic antidepressants

Abstract

The chromatographic behaviour (retention, selectivity, peak shape and resolution) of seven tricyclic antidepressants (TCAs), amitryptiline, clomipramine, doxepin, imipramine, maprotiline, nortryptiline and trimipramine, was examined. Conventional unendcapped C 8 and C 18 columns and an endcapped XTerra MS C 18 column recommended for the analysis of basic compounds were used together with acetonitrile–water and micellar sodium dodecylsulfate (SDS)–pentanol mobile phases. The two best combinations were XTerra C 18/acetonitrile, which yielded the largest efficiencies and resolution, and C 8/SDS–pentanol, which eliminated the peak tails that were still observed with the XTerra C 18 column. Both the systems were used to develop simple chromatographic procedures for the control of TCAs in pharmaceutical formulations using UV detection. The selected mobile phase compositions were 35% (v/v) acetonitrile (XTerra C 18 column) and 0.075 M SDS–6% (v/v) pentanol (C 8 column), both at pH 3. Satisfactory recoveries were achieved in both cases, with intra- and inter-day relative standard deviations (RSDs) always below 0.6 and 2.0%, respectively. The preparation of the samples was simple in both modes, since a previous extraction of the drugs was not needed. The micellar mode has, however, the advantage of using a smaller amount of organic solvent, which is retained in the micellar SDS solution. The C 8 column is also less expensive.