liquid junction

https://doi.org/10.1351/goldbook.L03584
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 [Terms] [Paper]