Theaflavins are a group of natural compounds found in black tea that are known for their potential health benefits. However, the presence of theaflavin impurities in tea products can reduce their effectiveness and quality. These impurities include theaflavin monomers, dimers, and polymers, which can be formed during tea processing and storage. Analyzing and controlling the levels of theaflavin impurities is important for ensuring the quality and health benefits of black tea products.