Validation of non-aqueous capillary electrophoresis for simultaneous determination of four tricyclic antidepressants in pharmaceutical formulations and plasma samples

We present the validation of a method using non-aqueous capillary electrophoresis (NACE) for quantitative analysis of four tricyclic antidepressants (TADs) in pharmaceutical formulations and plasma. The method presented high resolution allowing the separation of the TADs in 4.3 min at optimized conditions: 50 mM ammonium acetate, 1 M acetic acid in acetonitrile, capillary with 48 cm in length, 40 cm to the detector, and voltage of 30 kV. Acceptable precision (relative standard deviation R.S.D.14.1% from plasma samples) and linearity were achieved using the internal standard (IS) method. The limits of quantification determined for plasma, after liquid–liquid extraction (LLE), were between 30 and 50 ng ml−1. These values are beyond the plasmatic therapeutic concentration. Our results were found comparable or better than those described in the literature for high performance liquid chromatography (HPLC)-based methods.