Transition interval

{
  "id": "MLC-T-CHM-012233",
  "term": "Transition interval",
  "field": "Chemistry",
  "definition": "The range of concentration or activity of a chemical species over which an indicator undergoes a discernible change, such as a shift in color or fluorescence. For a pH indicator, this is the pH range, typically spanning one to two pH units, within which its color transitions from its acidic form to its basic form. This interval is centered around the indicator's pKa value, where the concentrations of the two forms are equal.",
  "subject": "Analytical Chemistry",
  "see_also": [
    "fluorescence"
  ],
  "references": [
    "Orange Book, 2nd ed., p. 48 (https://media.iupac.org/publications/analytical_compendium/)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/transition-interval/"
}