supporting electrolyte

https://doi.org/10.1351/goldbook.S06149
An electrolyte solution, whose constituents are not electroactive in the range of @A00424@ being studied, and whose @I03180@ (and, therefore, contribution to the conductivity) is usually much larger than the concentration of an @E01940@ to be dissolved in it.
Source:
PAC, 1985, 57, 1491. (Recommended terms, symbols, and definitions for electroanalytical chemistry (Recommendations 1985)) on page 1501 [Terms] [Paper]