Development and Validation of a QbD-Based UV Spectrophotometric Method for the Quantification of Silibinin Using Area Under the Curve (AUC) Approach

Abstract

Introduction: Reliable quantification of silibinin, a therapeutically significant flavonolignan, is essential for pharmaceutical analysis. A UV spectrophotometric method based on the Area Under the Curve (AUC) principle offers a simple, economical, and robust approach by minimizing wavelength-dependent variability. Integration of a Quality by Design (QbD) framework enables systematic method optimization and ensures reproducible and regulatory-compliant analysis.

Objectives: The aim of this study was to develop and validate a simple, rapid, and reliable UV spectrophotometric method based on the Area Under the Curve principle for the quantitative estimation of silibinin. The method was designed using a Quality by Design approach to ensure accuracy, precision, and robustness suitable for routine pharmaceutical analysis.

Methods: Absorbance readings were recorded within the wavelength range of 265.60 to 311.80 nanometres, with 289 nanometres selected as the central wavelength for AUC calculations. A Central Composite Design was applied to identify and optimise critical method parameters and to understand their influence on analytical performance. Following optimization, the method was validated according to the International Council for Harmonisation Q2 R1 guidelines, including assessments of linearity, accuracy, precision, and robustness

Results: The Quality by Design framework supported a systematic evaluation of analytical variables and facilitated the development of a stable and efficient method. The Central Composite Design enabled efficient screening of factors and optimisation of conditions. The method exhibited excellent linearity across the concentration range of 2 to 16 micrograms per millilitre, with a correlation coefficient of 0.9997. Precision studies demonstrated strong repeatability and reproducibility, with the coefficient of variation remaining below two percent. The method also showed good sensitivity and specificity, ensuring accurate quantification without interference. Validation results confirmed compliance with International Council for Harmonisation criteria.

Conclusions: The developed UV AUC method is simple, cost effective, and analytically sound. The Quality by Design based optimisation ensures robustness and consistency, making the method suitable for routine quality control and quantitative analysis of silibinin in pharmaceutical formulations.