This standard GB/T 15555.11-1995 specifies a method for the determination of fluoride in solid waste leaching solution, using the fluoride Ion selective electrode method. This method is suitable for the determination of fluoride concentration in the range of 0.05 mg/L to 1,900 mg/L. The fluoride electrode is sensitive to changes in fluoride Ion concentration in the Temperature range of 20 to 25 ° C, and the electrode slope should not be less than 55 mV. This method mainly determines the concentration of free fluoride ions, but in the presence of interfering ions such as Ca2 +, Mg2 +, Al3 +, Fe3 +, Si4 +, etc., the measurement results may be affected. In addition, ammonia oxide ions and fluoroborate ions can also interfere with the electrode Response. To ensure accuracy, the measurement needs to maintain an appropriate pH value (recommended 5~ 7) and total ion strength, and may require distillation treatment.