Stream Sediment and Soil Samples by Microwave Digestion Followed by ICP-MS Measurement

A critical study has been made for the determination of rare earth elements (REEs) and eight other low level elements (Be, Ge, Mo, Sn, W, Hf, Ta and U) in stream sediment and soil samples by microwave digestion, followed by ICP-MS measurement. In this study, 0.1 g samples were decomposed in a microwave sample digestion system with 1 mL HF, 1.5 mL HNO 3 , and 4 mL HCl at a pressure of 20 bar and a temperature of 200 °C for 30 minutes. The decomposition process was then repeated a 2 nd time. After decomposition, the sample was transferred into a Teflon beaker, 1 mL HClO 4 was added, and the acids evaporated to near dryness. The residue was dissolved in dilute HNO 3 , 10 mL of 100 ppb internal standard (indium) was added, and the solution transferred to a 100-mL volumetric flask. REEs and other trace elements were determined using a PerkinElmer SCIEX Model ELAN® DRC™-e ICP-MS spectrometer.