Total ionic strength adjustment buffers (TISAB) are buffer solutions that increase the ionic strength of a solution to a relatively high level. This is important for potentiometric measurements, including ion-selective electrodes, because they measure the activity of the analyte rather than its concentration. TISAB is very commonly applied to fluoride ion analysis such as in fluoride ion-selective electrodes. Each constituent of TISAB plays an important role in controlling the ionic strength and pH of the analyte solution.