This standard specifies a method for the determination of total fluorine content in coal samples or soil samples by ion-selective electrode for treating samples by high-temperature hydrolysis. It is suitable for the determination of total fluorine content in various coal and soil samples. The principle is that after the sample is mixed with quartz sand, it is converted into hydrogen fluoride or Miscellaneous volatile fluorine-containing compounds in combustion and hydrolysis with oxygen-water vapor flow at high temperature, and then absorbed with sodiumhydrate solution, and finally the fluorine content of the absorption solution is determined by ion-selective electrode. Reagent use requirements include the use of superior pure sodium fluoride and analytically pure Miscellaneous reagents, as well as the use of deionized water.