Any junction between two electrolyte solutions of different composition. Across such
a junction there arises a potential difference, called the liquid junction potential.
In the
operational pH cell the junction is between the test, or
pH standard, solution and the
filling solution or the
bridge solution of the
reference electrode.
Source:
PAC, 1985, 57, 531
(Definition of pH scales, standard reference values, measurement of pH and related
terminology (Recommendations 1984))
on page 541