This standard specifies a method for the determination of mg content in lithium by flame atomic absorption spectroscopy (AAS), suitable for the determination of mg content between 0.0010% and 0.01%. Method Absorbance of mg is determined at a wavelength of 285.2 nm by dissolving the sample in dilute muriatic acid medium using the Standard addition method. The standard describes in detail the preparation of the reagent, Sample Handling and measurement procedures to ensure the accuracy and conformity of the results, and is an important reference for the determination of mg content in lithium products.