Capillary electrophoresis as sample introduction system for highly sensitive and interference-free determination of 99Tc by ICP-MS

Abstract

Although inductively coupled plasma mass spectrometry (ICP-MS) retains high sensitivity and has been intensively used for the measurement of ⁹⁹Tc, it usually suffers from tedious, expensive, and time-consuming sample pretreatments due to the isobaric interferences from ⁹⁹Ru and ⁹⁸Mo¹H. Herein, capillary electrophoresis (CE) was applied as sample introduction system for the sensitive, and interference-free determination of ⁹⁹TcO₄^- from RuO₄^-, and MoO₄^2- by ICP-MS with a simple sample treatment. Compared to the conventional methods, the hyphenated CE-ICP-MS avoids the use of expensive separation resins and reduces the consumption of mineral acid, representing a simpler, more efficient and environmentally benign approach. Moreover, the proposed method exhibits higher accuracy compared with the mathematical correction method using the natural isotope ratio of ⁹⁹Ru and ¹⁰¹Ru, and significantly reduces sample consumption and the amount of waste, thus remarkably alleviating the radioactive exposure to operators and the pressure of radioactive waste treatment. Under the optimized conditions, the detection limits of 25 µg/L and 0.06 µg/L were obtained for RuO₄^- and ReO₄^- (Tc was replaced by Re), respectively, with relative standard deviation (RSD) lower than 5%. In addition, efficient recoveries of RuO₄^-, ReO₄^-, and ⁹⁹TcO₄^- from simulated Hanford site groundwater were achieved. The method is expected to be a promising candidate for sensitive and accurate analysis of ⁹⁹Tc from contaminated environmental samples.