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

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 Cs-133 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.