This research addresses a long-standing challenge in food and natural-product analysis: accurately distinguishing anthocyanins from other flavonoids. Anthocyanins are natural pigments responsible for red, purple, and blue colors in many fruits and vegetables and are widely valued for their antioxidant and health-promoting properties. However, in real biological samples, anthocyanins coexist with many chemically similar flavonoids, making correct identification difficult.
Conventional mass spectrometry methods often rely on automated workflows that can misassign precursor ions—the original charged molecules selected for fragmentation. When the wrong precursor ion is chosen, the compound may be incorrectly identified, leading to false confidence in the results. This problem is particularly serious for anthocyanins because they behave differently under positive and negative ionization conditions.
To solve this, the researchers developed a fast polarity-switching (FPS) mass spectrometry strategy, which rapidly alternates between positive and negative ion detection during a single analysis. They observed that anthocyanins show a characteristic positive-to-negative signal intensity ratio, while other flavonoids display very different patterns. This ratio acts as a reliable fingerprint for distinguishing anthocyanins.
Building on this concept, the team created an automated program called FPS_P/N, which integrates three steps: (1) screening candidate compounds using molecular networking, (2) determining the correct precursor ions using polarity-dependent intensity ratios, and (3) confirming identities through fragmentation patterns. In simple terms, the workflow ensures that the “right molecule” is selected before detailed analysis begins.
The method was validated using blueberry samples, where the researchers successfully identified 20 anthocyanins and 14 other flavonoids with high accuracy. Importantly, the approach reduces false annotations and improves reproducibility without requiring additional sample preparation or specialized chemical labeling.
The impact of this work is methodological but far-reaching. By improving confidence in anthocyanin identification, the strategy strengthens research in nutrition science, functional foods, plant chemistry, and metabolomics. It also demonstrates how smarter data acquisition and analysis—not just more powerful instruments—can significantly improve the reliability of chemical discovery in complex natural systems.
Reference
Y.-H. Ge, L. Zhang, S. Gong, W. Miao, L. Zhang, W. Bai, J.-L. Wu, and N. Li, “FPS_P/N: A two-dimensional mass spectrometry utilization program with precursor ion determination for accurately distinguishing anthocyanin from other flavonoids,” Journal of Pharmaceutical Analysis, 2025, doi: 10.1016/j.jpha.2025.101385.
