The invention discloses a
sample processing method for determining residual
lithium salt on a surface of a battery shell in a
flame atomic absorption spectroscopy method. The method comprises the following steps: cleaning and extracting the surface of a battery shell by using
dimethyl carbonate, continuously performing ultrasonic immersion for a battery eluted by the
dimethyl carbonate by using a
nitric acid solution to extract the
lithium salt, concentrating a
dimethyl carbonate extract solution, adding a
nitric acid solution, performing oscillation extract, and transferring a
nitric acid phase into the nitric acid extract solution; heating to remove the acid, transferring the residual solution into a volume
bottle after the acid removal, adding 1ml of 1 percent cesium
chloride, fixing the volume by using deionized water to obtain a solution to be detected; and performing the blank treatment by adopting a same method, and determining the sample to be detected and the blank sample by directly using the
flame atomic absorption spectroscopy method. By adopting a combined pretreatment means for dissolving the residual
lithium salt on the surface of the battery shell by using the dimethyl
carbonate and the nitric acid solution, and the lithium salt in the dimethyl
carbonate is extracted into the nitric acid solution by using a liquid-liquid extraction method, so that the interference of organic solvents is effectively avoided.