Determination of Arsenic and Selenium in Soil Samples by ICP-MS — Elimination of Interferences of Rare-earth Elements by Cation-exchange —

Abstract

In determining As and Se in soil samples by ICP-MS, doubly charged ions due to Nd, Sm, and Gd cause severe spectral interferences. In the present work, a separation method of Nd, Sm, and Gd by cation exchange was examined. As a result, it was found that Nd, Sm, and Gd could be removed by cation exchange when the concentration of HCl was smaller than 0.1 mol L⁻¹, while As and Se could be recovered quantitatively. The recovery values of As and Se were 104.7 ± 2.1 % and 100.3 ± 0.4 %, respectively, and their detection limits were 0.006 mg kg⁻¹ and 0.003 mg kg⁻¹; in the case that 1 mol L⁻¹ HCl extracted solution (6 g of soil sample was extracted with 200 mL of 1 mol L⁻¹ HCl) was diluted 50-times and treated with 0.40 g of cation exchange resin. The feasibility of the present method was examined by analyzing soil certified reference material (JSAC 0402). The present method was applicable for the determination of As and Se in various soil samples.