离子选择性电极直接电位法测定牙膏中游离氟

Determination of free fluorine in toothpaste by potentiometry with a fluorine ion selective electrode

利用氟离子选择性电极直接电位法测定了牙膏中的游离氟。讨论了总离子强度调节缓冲剂(TISAB)的组成及用量,氟电极在测定后快速恢复到空白值,以及不同空白值对测定结果的影响。实验结果表明游离氟的浓度在0.1000～9.000mg/ml范围内线性关系良好,方法的最低检出限为0.02000μg/ml,相对标准偏差RSD≤2.5％,加标平均回收率为100.8％～104.7％,方法简便,准确。

The content of free fluorine in toothpaste by potentiometry with a fluorine ion selective electrode is determined. It discusses that the composition and volume of TISAB, the fluorine electrode speedily coming back to blank value after determining sample and different blank values influence on the results. The results show that the detection limit is 0.02000μg·ml-1, the linear relation of free fluorine concentration is between 0.1000-9.000μg·ml-1, RSD≤2.5%, and the average recovery rate is 100.8%-104.7%.