钠离子选择性电极响应时间及其影响因素

研究了待测液浓度、温度、搅拌速度以及电极污染、老化等因素对钠离子选择性电极响应时间的影响,进行了相应的实验。实验结果表明,适当增加待测液浓度、温度、搅拌速度可以缩短钠离子选择性电极响应时间;电极的污染、老化会使电极敏感性下降,响应时间延长。

钠离子选择性电极法测定磷矿石中氧化钠

尝试用钠离子选择性电极法测定磷矿石中氧化钠的可能性。经实验验证 ,当氧化钠浓度在 10 -5～10 -1mol/L时 ,该法呈线性关系 ,符合能斯特方程 ,其响应斜率为 5 5mV。通过对标准样品的测定 ,它与原子吸收光度法相比 ,其相对标准偏差为 4.6 4%、7.89% ,平均偏差为 3 .13%、6 .6 7%。

氧弹燃烧-离子选择性电极法测定瓜子中的钠

采用氧弹燃烧-离子选择性电极法测定了瓜子中的钠含量。先将不同瓜子样品粉碎压制成片，利用氧弹燃烧技术进行预处理，用盐酸吸收燃烧产物；再在样品液中加入三乙醇胺溶液，调节样品溶液的pH为10左右，然后用钠离子选择性电极测定瓜子中的钠含量。测定结果表明：西瓜子中钠含量最多，葵瓜子钠含量最少，回收率在97.3%~98.6%，相对标准偏差在0.80%~1.70%之间。该法测定瓜子中的钠离子含量简便、快速且准确度高。

Direct Determination of Potassium-Sodium Activity Ratio in Soil Suspension with Two Ion-Selective Electrodes

A K+-selective electrode and a Na+-selective electrode were used to construct a measuring cell without liquid-junction for the determination of the ion activity ratio of K+ to Na+ in soil suspensions. The measured cell potential was not affected by the total electrolyte concentration when the total cation concentration was 10-1-10-3 mol L-1 and the concentration ratio CK+ / CNa+. was 10:1 to 1:50. When the concentration ratios were equal to 1and the total electrolyte concentrations were 10-2 and 10-3 mol L-1, the ion activity ratio measurement would not be affected by pH in the pH range of 3.5 to 11.5 and 4.4 to 11 respectively. Ions other than H+ have no remarkable influence on the measurement. The ion activity ratio of K+ to Na+ measured directly in soil suspension agree well with those in centrifuged supernant solution. The relative deviation was within 4%. From the measured ion activity ratio, the difference of the bonding energies of K+ and Na+ ions was calculated.