摘要
建立了溶液法制样-X射线荧光光谱法(XRFS)测定天然铀产品(U_(3)O_(8))中铀元素的含量,并从样品中锶含量水平、锶元素分析谱线的选择、锶内标化合物的选择、样品中硫含量对锶的影响等角度探讨了锶内标法的可行性。将0.600 00 g干燥后的内标物碳酸锶与1.000 00 g天然铀产品(U_(3)O_(8))混合,用磷酸和硝酸在电炉上加热消解,吸取20 g消解液于塑料样杯中,按照优化的XRFS仪器工作条件测定。以标准物质GBW 04205配制的标准溶液系列制作标准曲线,并引入了标准曲线的参数建立校正公式,以消除基体效应。结果显示:样品中锶的质量分数不大于8.0μg·g^(-1),硫的质量分数小于2.00%,均不影响锶内标法对铀的测定;内标物碳酸锶的用量为0.600 00 g时,以锶元素的Kα作为内标特征线测定,锶元素和铀元素的荧光强度及吸收-增强效应基本一致,且不受样品溶液的定容体积、进样量和仪器波动的影响;铀标准曲线的线性范围为78.78%~87.25%;对标准物质GBW 04205平行分析11次,测定值的相对标准偏差(RSD)为0.061%,测定值(84.722%)与认定值(84.711%)的绝对差值为0.011%,小于天然铀产品(U_(3)O_(8))贸易检测中铀元素的质控指标(0.1%);方法用于6个实际样品的分析,测定值与国家标准GB/T 11848.1-1989中的电位滴定法所得的测定值基本一致。
A method for the determination of uranium in natural uranium product(U_(3)O_(8)) was established by X-ray fluorescence spectrometry(XRFS) after preparation of sample with solution method. The feasibility of the strontium internal standard method was discussed from the aspects of strontium level in sample, the selection of strontium analytical spectral line, the selection of strontium internal standard compound, and the effect of sulfur content in sample on strontium. 0.600 00 g of dry internal standard strontium carbonate was mixed with 1.000 00 g of natural uranium product(U_(3)O_(8)), and the mixture was digested with phosphoric acid and nitric acid under the heat condition on an electric stove. The digestion solution(20 g) was taken into a plastic sample cup, and determined under the optimized working conditions of XRFS instrument. Standard solution series prepared by standard material GBW 04205 were used to make standard curve, and parameters of which were introduced to establish the correction formula to eliminate matrix effect. The results showed that mass fraction of strontium in sample was not more than 8.0 μg·g^(-1) when mass fraction of sulfur was less than 2.00%, which did not affect the determination of uranium by strontium internal standard method;when the amount of internal standard strontium carbonate was 0.600 00 g and the Kα of strontium was used as an internal standard characteristic line, the fluorescence intensity and absorption-enhancement effect of strontium and uranium were basically the same, and the determination of uranium was not affected by the constant volume of sample solution, injection volume and instrument fluctuation. Linear range of uranium of standard curve was found in the range of 78.78%-87.25%. The standard material GBW 04205 was analyzed 11 times in parallel, RSD of the determined values was 0.061%, and the absolute difference between the determined value(84.722%) and the certified value(84.711%) was 0.011%, which was less than quality control index(0.1%) of uranium in the trade detection of natural uranium product(U_(3)O_(8)). The proposed method was applied to the analysis of six actual samples, with determined values basically consistent with those obtained by potentiometric titration of national standard GB/T 11848.1-1989.
作者
柳金良
宋茂生
张鑫
岳中慧
范鹏飞
LIU Jinliang;SONG Maosheng;ZHANG Xin;YUE Zhonghui;FAN Pengfei(Changsha Uranium Geology Research Institute,CNNC,Changsha 410007,China)
出处
《理化检验（化学分册）》
CAS
CSCD
北大核心
2021年第9期824-829,共6页
Physical Testing and Chemical Analysis(Part B:Chemical Analysis)
基金
中国核工业地质局铀矿地质项目(201917-4)。
