When sourcing Naringenin, the primary quality indicator is the purity level, which should typically be ≥98% via HPLC (High-Performance Liquid Chromatography) for pharmaceutical or high-end nutraceutical use. Buyers must request a Certificate of Analysis (COA) for every batch to verify the melting point (247-250°C) and ensure that heavy metal content (Lead, Arsenic, Mercury) is within the safety limits of <10ppm. Additionally, confirm the botanical source, usually derived from Citrus maxima (pomelo) or Citrus paradisi (grapefruit), as natural extraction is often preferred over synthetic alternatives in the health supplement market.