| 摘要 |
Reference electrodes for potentiometric measurement of pH and ion concent ration typically use mercury calomel or silver/silver chloride element combi ned with a saturated solution of potassium chloride (KC1) for the developmen t of a stable potential with respect to a sensing electrode when immersed in solution. The salt KC1 is preferred because of it is almost equitransferent and thus minimizes the diffusion potential set up between the reference sol ution and the solution being tested. However, reference electrodes using con centrated solutions of KC1 suffer a drawback, which is its propensity to dev elop a creeping salt discharge that rapidly covers surfaces with KC1 crystal s. This "salt creep" phenomenon appears to be unique to KC1; Salt creep is a major nuisance, particularly for reference electrodes used on semi-dry surf aces such as skin. It has been found that adding a secondary salt, such as s odium chloride on its own or with an evaporation inhibiting agent in selecte d ranges inhibits salt creep without adversely affecting the other propertie s of the reference solution. |
