Lee C O
Biophys J. 1979 Aug;27(2):209-20. doi: 10.1016/S0006-3495(79)85212-1.
Electrochemical properties of Na+-selective glass microelectrodes were studied and compared with those of K+-selective glass microelectrodes. The selectivity of Na+-selective glass microelectrodes depended on the ion concentration of test solutions. With aging, resistance of Na+-selective microelectrodes increased and their selectivity for Na over K decreased. Na+-selective microelectrodes potential measured in NaCl solution remained constant with aging, while the potential measured in KCl solution decreased and became more positive. The changes in resistance and potential of Na+-selective microelectrodes may be due to the effects of the less mobile cation, i.e., H+ or K+ on the Na ion exchange in the Na-sensing region. The results indicate that Na+-selective microelectrodes must be used as soon after filling as possible. The selectivity of Na+-selective microelectrodes increased with increase of the sensitive exposed-tip length, whereas their response time became slow due to a large recessed volume, indicating requirement of an optimum exposed-tip length for intracellular applications. The changes in the properties of Na+-selective glass microelectrodes with aging contrasted with those of K+-selective glass microelectrodes in which resistance decreased and K+-selectivity increased. The K+-selective microelectrodes required aging before use for a high selectivity and low resistance. The K+-selective microelectrodes with low resistance after sufficient aging can be used without insulation to measure K+ and Na+ activities in aqueous solutions. The different properties between Na+- and K+-selective microelectrodes are understandable, because hydration of N+-selective glass is much less extensive than that of K+-selective glass.
研究了钠选择性玻璃微电极的电化学性质，并与钾选择性玻璃微电极的电化学性质进行了比较。钠选择性玻璃微电极的选择性取决于测试溶液的离子浓度。随着老化，钠选择性微电极的电阻增加，其对钠相对于钾的选择性降低。在氯化钠溶液中测量的钠选择性微电极电位随老化保持恒定，而在氯化钾溶液中测量的电位降低并变得更正。钠选择性微电极电阻和电位的变化可能是由于迁移率较低的阳离子（即H+或K+）对钠传感区域中钠离子交换的影响。结果表明，钠选择性微电极必须在填充后尽快使用。钠选择性微电极的选择性随着敏感尖端暴露长度的增加而增加，而由于凹陷体积较大，其响应时间变慢，这表明细胞内应用需要最佳的尖端暴露长度。钠选择性玻璃微电极性质随老化的变化与钾选择性玻璃微电极相反，钾选择性玻璃微电极的电阻降低，钾选择性增加。钾选择性微电极在使用前需要老化以获得高选择性和低电阻。充分老化后电阻较低的钾选择性微电极可以不进行绝缘处理用于测量水溶液中的钾和钠活性。钠选择性和钾选择性微电极之间的不同性质是可以理解的，因为钠选择性玻璃的水合程度远低于钾选择性玻璃。
