Determination of natural Sr and 90Sr in environmental samples by ETV-ICP-MS

Abstract

The determination of Sr in environmental samples by electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) is described. Two ETV devices, a commercially available HGA-600MS graphite tube unit and a home-made W-coil, were examined in combination with DRC technology to remove isobaric interferences when measuring ⁹⁰Sr. Best results were obtained using the HGA-600MS device. Interferences from Y and Zr could be removed when these elements were present at concentrations up to 1 and 100 mg kg⁻¹, respectively, an improvement of 15 and 30-fold over solution nebulization. Temporal separation of analyte and isobaric interferents makes possible the use of simplified sample preparation procedures, substantially increasing sample throughout and reducing the chances of analyte loss or contamination. For the graphite-based HGA system, procedural LODs of 3.5 pg g⁻¹ could be obtained with precision better than 7% at 350 pg g⁻¹. The accuracy of the method was validated by determination of natural Sr in NRC CRM MESS-3 (Marine Sediment), LUTS-1 (Non Defatted Lobster Hepatopancreas), PACS-2 (Marine Sediment) and SLRS-4 (Riverine Water) and by recovery of ⁹⁰Sr spikes added to these matrices.