Determination of Minoxidil by Bleaching the Permanganate Carrier Solution in a Flow-Based Spectrophotometric System

Abstract

The determination of minoxidil (MX) with potassium permanganate as a carrier in a flow injection method is described. The detection at 550 nm was linear from 1.0 × 10⁻⁵ to 5.0 × 10⁻⁴ mol L⁻¹. The limit of detection (3σ/slope) was 8.92 × 10⁻⁶ mol L⁻¹, with an analytical frequency of 32 h⁻¹. The proposed method was applied to commercial samples, with recoveries from 104.7 to 106.4%. Comparison with the HPLC procedure reveled relative errors from 0.48 to 1.4%, and the results agreed within a 95% confidence level.

Keywords:

• Antihypertensive drug analysis
• Flow injection
• Minoxidil
• Permanganate bleaching
• Spectrophotometric detection

Acknowledgments

This paper was submitted as part of a Special Issue on Flow Injection Analysis.

The authors are grateful to FAPESP (Proc n° 08/03537-7), for financial support and Programa PROCONTES/USP for PC support.

Notes

A = reactor; B = sample loop; C = flow rate.

a = mg mL⁻¹ ± Standard deviation, n = 10.

b = |Relative Error| = [(FIA – HPLC)/HPLC] ∗100%.