IJUP08 - Universidade do Porto

Development of an automatic multi-pumping flow system for the
spectrophotometric determination of trimipramine
D. Ribeiro 1 , J. Prior 1 , J. Santos 1 and J. Lima 1
1 Requimte, Department of Physical-Chemistry, Faculty of Pharmacy, University of Porto,
Portugal.
Trimipramine maleate, is a tricyclic antidepressant agent, that belongs to the
dibenzoazepine class, with an anxiety-reducing sedative activity. The intensive
therapeutical utilisation of dibenzoazepine derivates increases the need to improve or
develop new methods for their determination in body fluids and in pharmaceutical
preparations [1].
In the present work, an automatic methodology of flow analysis exploiting the multipumping
[2] concept was developed for the spectrophotometric determination of
trimipramine in commercially available pharmaceutical formulations. The trimipramine
determination was based on the reaction of the drug with ammonium monovanadate
reagent in acidic medium yielding a coloured compound with a maximum of absorbance at
620 nm [3]. The improved flow mixing conditions during sample and reagents insertion
and transport, due to the chaotic movement of the solutions originated by the pulsed flow
characteristic of multi-pumping systems, assured a fast reaction zone homogenization in a
reduced residence time, which was particularly advantageous for carrying out analytical
determinations that involved highly viscous solutions, as is the case of the sulphuric acid
solution used in the determination of trimipramine, without impairing the sampling rate.
A linear working range for trimipramine concentrations of up to 50 mg L-1 (r = 0.9998; n
= 6) was obtained and the detection limit was about 1.15 mg L-1. The sampling rate was
approximately 50 determinations per hour. The obtained results were in agreement with
those furnished by the reference procedure [4], with relative deviations lower then 4.7%.
The proposed methodology allowed the rapid quantification of trimipramine, which could
represent an advantageous alternative for the pharmaceutical control at industrial level, and
additionally, required low quantities of reagents and produced reduced volumes of
residues.
References:
[1] Baldessarini, R.J. (2001), Drugs and the treatment of psychiatric disorders. Depression and
anxiety disorders, in Gilman, A.G., Hardman, J.G., and Limbird, L.E. (Eds.) The pharmacological
basis of therapeutics, 10th ed., New York: McGraw Hill Co., pp. 447-483.
[2] Lapa, R.A.S., Lima, J.L.F.C., Reis, B.F., Santos, J.L.M., Zagatto, E.A.G. (2002), Multipumping
in flow analysis: concepts, instrumentation, potentialities, Anal. Chim. Acta, 466, 125-
132.
[3] Misiuk, W. (2000), Spectrophotometry assay of imipramine and desipramine using ammonium
metavanadate and its application to pharmaceutical preparations, J. Pharm. Biomed. Anal., 22, 189-
196.
[4] Trimipramine Maleate monograph, tablets (2005), in British Pharmacopoeia, vol. III, London:
The Stationary Office, pp. 2853.
37