PURPOSE: To obtain an ICP method for quantifying silicon in an Al-Si electrode with high sensitivity so as to grasp the quantitative relationship between the blending composition and characteristics of the Al-Si electrode.

CONSTITUTION: Dilute hydrochloric is added to a sample collected from an Al-Si electrode. The sample is heated at predetermined temperatures to be decomposed, and thereafter cooled. Purified water and strontium as a standard reference material are added to the decomposed solution. A constant amount of the liquid is obtained by the purified water as a sample solution. The light emitting intensity of silicon of the sample solution is measured by the high frequency induction coupling-type plasma emission method. Accordingly, a method for quantitative analysis of silicon to quantify silicon by the internal standard method is achieved.