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目的研究溶液pH值及Fe~(3+)、Mn~(2+)对铀酰离子荧光特性的影响。方法采用紫外荧光法测量液体样品中的微量铀。结果溶液pH值在3~10时对标准加入法测微量铀无明显影响;pH值为6左右时,单位铀浓度增长所对应的荧光增长计数最多,测量结果最接近标准值,pH值为13左右时已无法进行测量。Fe~(3+)、Mn~(2+)会熄灭铀的荧光,对测量产生负干扰,1 ng/m L铀溶液中Fe~(3+)的最大允许量为10μg/mL,Mn~(2+)的最大允许量为0.1μg/mL;可通过预处理或适当稀释样品溶液的方法来降低Fe~(3+)、Mn~(2+)的干扰。结论采用标准加入法测量时应尽量控制p H值在3~10之间;Fe~(3+)、Mn~(2+)与荧光增强剂形成的络合物会吸收紫外光,对铀的测量产生负干扰。当待测样品铀浓度超出测铀量程是测量结果偏高,无法得出准确结果。
Objective To study the effects of pH and Fe ~ (3 +) and Mn ~ (2+) on the fluorescence characteristics of uranyl ion. Methods Uranium fluorescence was used to measure trace uranium in liquid samples. Results When the pH was between 3 and 10, there was no obvious effect on the uranium content of the standard addition method. When the pH value was about 6, the uranium enrichment corresponded to the highest fluorescence growth counts. The measured value was closest to the standard value and the pH value was 13 Left and right can not be measured. The maximum permissible amount of Fe 3+ in 1 ng / m L uranium solution was 10 μg / mL with Fe ~ (3 +) and Mn ~ (2+) quenching uranium fluorescence and negatively affecting the measurement. (2+) is 0.1μg / mL. The interference of Fe ~ (3 +) and Mn ~ (2+) can be reduced by pretreatment or appropriate dilution of the sample solution. Conclusion The p H value should be controlled between 3 and 10 when measured by standard addition method. The complex formed by Fe 3+, Mn 2+ and fluorescence enhancer will absorb UV light and the fluorescence intensity of uranium Negative interference measurement. When the uranium concentration of the sample to be tested exceeds the measuring range of uranium, the measurement result is too high to be able to obtain accurate results.