Direct determination of trace cadmium in environmental samples by dynamic reaction cell inductively coupled plasma mass spectrometry

Abstract

Cadmium is subject to significant Zr and Mo based oxide/hydroxide interferences in ICP-MS analysis of environmental samples. In this work, a dynamic reaction cell (DRC) technology was used to eliminate these metal oxide/hydroxide interferences. The potentially interfering ions 94Zr 16OH +, 94Mo 16OH + and 95Mo 16O + on 111Cd + were oxidized to higher oxides 94ZrO 2H +/ 94ZrO 3H +, 94MoO 2H +/ 94MoO 3H +, and 95 MoO 2 + / 95 MoO 3 + by O 2 as the reaction gas in DRC. Under the optimized O 2 flow rate (2.0 mL min −1) and DRC rejection parameter q (Rpq, 0.75), the background signal was reduced by up to 100-fold at m/z 111 and the limit of quantitation (LOQ, 10σ) of 0.1 ng g −1 was obtained. The proposed method was applied to direct analysis of trace Cd in a series of soil and sediment standard reference materials and the satisfactory results showed that it has great potential for the direct determination of trace or ultra-trace levels of cadmium in environmental samples.