"TCVN 5612-2007 Tea. Determination of acid-insoluble ash" is a standard on the determination method of tea folic acid insoluble ash. The standard specifies the specific operation steps for ash determination at high temperature using the sample after acid dissolution. Acid-insoluble ash is determined by reacting with certain components in tea leaves through an acidic solution. After removing soluble substances, it is determined by heating the remaining solid substances. The standard is of great significance for ensuring tea quality control, product conformity, and the formulation of tea-related mass standards. Accuracy and reliability of measurement results are ensured through standardized operating procedures.