Spectrophotometric Determination of Trimipramine in Tablet Dosage Form via Charge Transfer Complex Formation

Purpose: To develop and validate simple, rapid and sensitive spectrophotometric procedures for determination of trimipramine in tablet dosage form.
Methods: The methods were based on the interaction of trimipramine as n-electron donor with the -acceptor, iodine and various -acceptors, namely: chloranil (CH), chloranilic acid (ChA), 2,3-dichloro-5, 6-dicyano-1, 4-benzoquinone (DDQ), and 7, 7,8, 8 tetracyanoquinodimethane (TCNQ), to form charge transfer complexes. The complexes obtained were measured spectrophotometrically at 292, 220, 520, 302, and 824 nm for I₂, CH, ChA, DDQ, and TCNQ, respectively. Different variables affecting the reaction were carefully studied and optimized.
Results: Beer's law was obeyed over the concentration ranges 1 - 5, 5 - 50, 15 - 100, 5- 50, and 10 -75 ppm for I₂, CH, ChA, DDQ, and TCNQ respectively, with apparent molar absorptivities of 7.1 x 10⁴, 0.3 x 10⁴, 1.6 x 10⁴, 0.26 x 10⁴, and 0.1 x 10⁴ l mol^-1cm^-1 respectively. The proposed methods were successfully applied to the determination of trimipramine with good accuracy and precision.
Conclusion: The results demonstrated that the developed methods are as accurate, precise and reproducible as the pharmacopeial method. The methods would be valuable for routine application in quality control.