Ca^(2+)和F^-对偶氮胂Ⅲ分光光度法测钐含量的影响

Effects of Ca^(2+) and F^- on Determination of Samarium by Spectrophotometry with Arsenazo Ⅲ

偶氮胂Ⅲ分光光度法是测定元素钐的重要手段。但是,溶液中有共存离子Ca^(2+)、F^-会对计量产生一定的干扰。通过改变溶液中Ca^(2+)、F^-含量,研究它们在偶氮胂Ⅲ分光光度法测定钐中的影响规律。实验结果表明,当溶液中不含Sm^(3+)时,F^-浓度的变化对吸光度没有影响;当溶液中含有Sm^(3+)时,随着F^-浓度的增加,溶液吸光度减小。随着Ca^(2+)浓度的增加,溶液吸光度呈明显增大趋势,但当溶液中含有Sm^(3+)时,Ca^(2+)对吸光度增大幅度有减弱的趋势。最后,获得了溶液中同时存在CaCl_2、CaF_2时对偶氮胂Ⅲ分光光度法检测Sm元素吸光度影响的定量规律,其最大相对误差为2.70%。

Spectrophotometric method with arsenazo Ⅲ is an important method for determination of samarium as a rare earth element. However, previous studies have shown that, existing of Ca2＋ and F- ions in the solution will have some interference to the measurement. In this paper, through changing the content of Ca2 ＋ and F - in the solution, the influence on the determination of samarium in spectrophotometry with arsenazo Ⅲ had been studied. The results show that, when Sm3＋ has not in the solution, changing of F- concentration has no effect on the absorbance as the signal of measurement, while the absorbance decreases with the increase of F - concentration in the solution of Sm3 ＋ contained. With the increase of Ca2 ＋ concentration in the solution, the absorbance is significantly increasing, but when the solution contains Sm3＋ , the increasing trend is weakened. Finally, the quantitative relationship with CaCl2 and CaF2 on the absorbanee is obtained, in which the maximum of relative error is 2.70 %.