Extraction and determination of Cs in natural waters by ICP-MS after ion exchange separation

Abstract

This article describes a novel and fast technique for the separation, preconcentration and determination of caesium in aqueous samples at sub-ppt levels using ion exchange separation and ICP-MS. The scheme is proposed for the extraction of radioactive caesium from the sample matrix. A new separation technique for the determination of caesium by inductively coupled plasma mass spectrometry is developed. Water samples with a pH less than 4 are loaded onto an ammonium molybdophosphate column at a flow rate of 8 mL min⁻¹. Elution of Cs from the AMP is accomplished using sequential extraction by NH₄OH (elutes AMP), H₂O (elutes excess AMP) and finally HNO₃ (elutes Cs). Preconcentration and separation of caesium from various sample matrices (sea-water and freshwater) was performed. Interferences (isobaric, polyatomic and matrix effects) were reduced using the developed protocol. Minimum detection limits for the determination of ¹³³Cs in a 1 L sample of water were found to be 0.02 ng L⁻¹ and 0.2 ng L⁻¹ using an ELEMENT-2 and an ELAN-5000 ICP-MS, respectively.