This standard specifies a method for the determination of calcium content in lithium by flame atomic absorption spectroscopy (AAS), suitable for the determination of calcium content in the range of 0.0010% to 0.1%. The method involves dissolving the sample in a dilute muriatic acid medium and measuring the calcium Absorbance by acetylene-nitrous oxide flammable flame at a wavelength of 422.7 nm. The standard details reagent preparation, instrument calibrating and operating procedures to ensure measurement accuracy. This method is suitable for quality control and testing of lithium products.