Analytical Characterization and Quantification of Plant-Derived Antioxidants Focusing on Methods, Limitations, and Data Comparability

Abstract The chemical characterization and quantification of plant-derived antioxidants are analytically challenging due to their structural diversity, low abundance, and pronounced matrix effects. This review critically examines the main analytical methodologies applied for the qualitative and quantitative assessment of antioxidant compounds in plant-based matrices, focusing on method performance, limitations, and data comparability rather than biological or clinical outcomes. Recent literature published between 2023 and 2025 was analyzed to identify prevailing analytical trends and methodological gaps. Chromatographic techniques, particularly high-performance liquid chromatography coupled with diode array detection and mass spectrometry, remain the primary tools for compound-specific identification and quantification, offering high selectivity and sensitivity in complex matrices. However, variability in extraction strategies, chromatographic conditions, detector selection, and calibration approaches continues to limit inter-study comparability. Spectroscopic techniques, including Fourier transform infrared spectroscopy and nuclear magnetic resonance, are increasingly used as complementary tools for structural elucidation and rapid screening. However, their standalone application is constrained by limited sensitivity and specificity. Antioxidant activity assays and total phenolic content measurements remain widely applied due to their simplicity; however, their analytical limitations—such as non-specificity, condition-dependent responses, and restricted quantitative relevance—are highlighted. Overall, this review emphasizes the need for harmonized, validated, and transparently reported analytical workflows, as well as the strategic integration of complementary techniques, to improve robustness and comparability in food antioxidant analysis.