GB/T 8309 - 2013 focuses on the determination of tea water-soluble ash alkalinity. It specifies the scope of applicable tea samples, details the collection and preparation methods of samples, specifies the required equipment, strictly regulates the operation process from Sample Handling, extraction to titration, and the calculation and representation of results. Water-soluble ash alkalinity can reflect the quality characteristics of tea leaves. This standard provides a unified measurement specification for the tea industry, helps to accurately evaluate the mass of tea leaves, and promotes the standardization of tea testing.