GB/T 12658-2008 "Determination of Sodium Content in Paper, Board and Pulp" specifies the method for determining sodium content using flame emission spectrometry or flame atomic absorption spectrometry after dry or wet digestion. This standard applies to pulp, paper, and board for electrical insulation, as well as to general pulp, paper, and board, with the sample amount adjustable based on the sodium content. It clearly outlines the procedures for sample digestion, instrument calibration, and testing steps, with a detection limit of 2 mg/kg achievable by flame emission spectrometry, providing data for quality control of related products.