Nonpolar solvent, reference electrodes

Reference Electrodes for Use in Nonpolar Solvents. Solvents such as dichloromethane (not highly polar) present special problems. Their low dielectric constants promote extensive ion association, and cell resistances tend to be large. For this reason they are often used in mixtures with more polar solvents. Because dichloromethane and other nonpolar solvents are not miscible with water, use of an aqueous reference electrode with such solvents is not practical unless a salt bridge with some mutually miscible solvent is used. A better approach is to use a reference electrode of known reliability prepared in a solvent miscible with dichloromethane or to use the reference electrode based on the half-cell in dichloromethane.88... 

Fig. 12. Design of the galvanic cell with a flat liquid-liquid interface. (A) The four-electrode type of cell with the aqueous (w, w ) and the organic solvent (o) phases, silver/silver chloride reference electrodes (1,4), platinum counter electrodes (2, 3), a glass barrier with a round hole for the liquid-liquid interface (5) and a tube connected to a syringe for adjustment of the interface. (After [158]). (B) The two-electrode type of cell with the aqueous (1,3) and organic solvent (2) phases, water jacket (4), PTFE silicone rubber (5), silicone rubber cap, silver/silver chloride reference electrodes (7,8), glass tube (9) and polarized working (w) or nonpolarized reference (r) interface. (After [42]).

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