Quality assessment of Bupleurum chinense by coupling Belousov-Zhabotinsky oscillation with principal component analysis

This study established a comprehensive analytical methodology utilizing Belousov-Zhabotinsky (B-Z) oscillation patterns coupled with principal component analysis for quality evaluation of medicinal herb extracts. The optimized system employed a two-electrode configuration with platinum working electrode (d = 2.0 mm) and demonstrated characteristic temporal evolution across three distinct phases. Systematic parameter optimization revealed optimal conditions including H₂SO₄ (3.0 mol/L), malonic acid (0.4 mol/L), and KBrO₃ (0.3 mol/L) concentrations. High-quality samples exhibited distinctive oscillation characteristics including maximum amplitudes of 0.09–0.14 V and mean oscillation periods between 16 and 23 seconds, with amplitude decay following pseudo-first-order kinetics (decay constants 2.3 ×10⁻³ to 3.8 ×10⁻³ s⁻¹). The analytical method showed excellent precision with relative standard deviations below 4 % for key parameters, particularly peak potentials (RSD = 1.7 %). Hierarchical cluster analysis initially revealed three distinct quality clusters; however, by further integrating quantitative oscillation parameters (e.g., ΔEₘₐₓ, induction time, and oscillation lifetime) and their correlations with traditional quality markers, these clusters were refined into five quality grades, thereby providing a more detailed evaluation framework. The method's robustness was confirmed through stability testing, showing minimal sensitivity to temperature variations ( ± 2°C) and reagent concentration fluctuations ( ± 2 %). Analysis of 30 samples from three geographical origins demonstrated clear regional quality patterns, with Q2 values of 0.85 and 0.78 for PC1 and PC2 respectively, enabling reliable geographical source discrimination.