Automatic Multipumping Flow System for Handling Viscous Solutions: Application to the Spectrophotometric Determination of Trimipramine

Abstract

The present work describes the implementation, by using MultiPumping Flow Analysis System (MPFS), of a spectrophotometric method for the determination of trimipramine in commercially available pharmaceutical formulations, based on the reaction with ammonium monovanadate in acidic medium yielding a colored compound with a maximum of absorbance at 620 nm. The improved flow mixing conditions during sample and reagents insertion and transport, as a result of the chaotic movement of the solutions originated by the MPFS pulsed flow, 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 sulfuric 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 determined 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, with relative deviations lower than 4.7%. With the developed MPFS, the consumption of the reagents ammonium monovanadate and sulfuric acid was reduced by approximately 41.02% and 54.29%, respectively, compared with a previously proposed multicommutated flow analysis system.

Keywords:

• Flow analysis
• multipumping
• pulsed flow
• trimipramine
• viscous solutions

Notes

∗Not mentioned.

^a Mean ± t _0.05 (Student's t test) × .

^b Relative deviation of the developed method regarding the reference procedure.