PLS Regression in the Spectrophotometric Data for the Simultaneous Determination of Levodopa and Carbidopa in Pharmaceutical Preparations by Using an Enzymatic Stopped‐Flow FIA Technique

Abstract

An enzymatic stopped‐flow‐injection analysis is proposed for simultaneous determination of levodopa and carbidopa in pharmaceutical preparations. The dopaquinones obtained after the oxidation catalized by the enzyme were measured by spectrophotometric method. A reduced calibration matrix based on a central composite experimental design was built and Partial Least Squares (PLS) was applied on the spectral data after reaction with the enzyme. The LOD was 0.015 and 0.0028 mg ml⁻¹, respectively and the sample throughput was 22.5 h⁻¹. The proposed method was applied to pharmaceutical preparations and the results are in close agreement with pharmacopeial method. The recovery study and results were satisfactory.

Keywords:

• Levodopa
• carbidopa
• stopped‐flow FIA
• polyphenol oxidase
• PLS

Acknowledgments

M. Grünhut and B.S. Fernández Band acknowledge CONICET (Consejo Nacional de Investigaciones Científicos y Técnicas) for support. All authors are gratefully acknowledged to Universidad Nacional del Sur.