| 摘要 |
<p>Reference electrodes for potentiometric measurement of pH and ion concentration typically use mercury calomel or silver/silver chloride element combined with a saturated solution of potassium chloride (KCl) for the development of a stable potential with respect to a sensing electrode when immersed in solution. The salt KCl is preferred because of it is almost equitransferent and thus minimizes the diffusion potential set up between the reference solution and the solution being tested. However, reference electrodes using concentrated solutions of KCl suffer a drawback, which is its propensity to develop a creeping salt discharge that rapidly covers surfaces with KCl crystals. This "salt creep" phenomenon appears to be unique to KCl; Salt creep is a major nuisance, particularly for reference electrodes used on semi-dry surfaces such as skin. It has been found that adding a secondary salt, such as sodium chloride on its own or with an evaporation inhibiting agent in selected ranges inhibits salt creep without adversely affecting the other properties of the reference solution.</p> |
