【摘要】 本文采用在4.0ml测定体系(2.0ml总离子强度液,1.0ml去离子水,1.0ml样液)以微量进样器加入2.0μg(20μl液量)标准氟的固定氟量添加法,对含氟量较低样品进行氟测定探讨。结果表明,在样品含氟0.04～1.0μg的测定体系中,添加前后的电位值差Δmv与氟含量在半对数图纸上显示良好的直线线性关系,向两端延长逐渐偏离直线,但根据曲线图,仍可用于1～4mg/L样品进行测定。方法研究表明各标准点的Δmv值基本稳定,10天内各标准点测定的变异系数为0.74～1.78％,样品测试结果表明精密度良好,同一水源样品7次采样测定其变异系数为4.19％,不同样品的回收试验表明,回收率为96.0～106.0％,平均值±标准差为99.93±3.14％,变异系数为3.14％。本法的另一特点是不受过量镁离子干扰,在给以大量镁盐的测定体系中,用能斯脱标准曲线法测定值明显低,回收率不足70％,而同样材料应用本法测定则回收率为99.2％,且测定的精密度仍较好(变异系数为1.7％)。因此,只要严格掌握好电极平衡点,固定氟量添加法可满足一般低氟水平样品氟的测定。更多还原

【Abstract】 The authors report a new analytical method of the fluoride using the fluoride electrade for the sample contained low fluoride level. In this method,adosage of fluoride (2.0 ug F) is added to 4ml analytical solution (TISAB 2.0 ml, sample 1.0ml, distilled water 1.0 ml) , both values of millivolt are read before and after, and then their difference (mv) is calculated. With the results of mv of each standard point , a standard graph on a semilogarithmic paper can be made for the calcularion of the fluoride content. The relationship between the and the fluoride level showed a linear relation in semilogarithmic graph as the fluoride content ranged 0.04-1.0ug.The coefficient of variation of mv on each standard points (0.05, 0.10, 0.5, 1.0ug F) was 0.74-1.78% tested within 10 days.The recovery rare of standard fluoride added in the sample was 96.0-106.0% in seven samples.The interference of Mg which is obvious in Nenst’s method was avoided in this new method.更多还原