GB/T 18882.2-2008 focuses on the determination of the amount of aluminum trioxide in ionic rare earth ore mixed rare earth oxides. The standard describes the determination principle, specifies the required reagents, instruments and equipment, and details the operation process from Sample Handling to specific determination, including solution preparation, titration steps, etc. Through standardized determination methods, the content of aluminum trioxide can be accurately obtained, providing key data for the mass evaluation of ionic rare earth ore mixed rare earth oxides, helping the production and quality control of rare earth industry, and promoting the standardization of related testing work.