GB/T 20975.9-2008 provides for the determination of lithium content in aluminum and aluminum alloys by flame atomic absorption spectroscopy (AAS). The aluminum and aluminum alloy samples are first processed to dissolve the lithium element into the solution. Lithium atomization is made using a Flame atomization device, and the light spectrum instrument measures the absorption degree of lithium atoms to specific wavelengths of light (Absorbance). The lithium content is calculated from Absorbance according to the pre-established lithium standard Linear dispersion. Sample Handling, instrument operation, measurement conditions and data processing are all specified in detail, providing an important means for mass testing of aluminum and aluminum alloy products, helping to accurately control lithium content and ensure product performance.