Comparison of laser ablation, electrothermal vaporization and solution nebulization for the determination of radionuclides in liquid samples by inductively coupled plasma mass spectrometry

The performance of solution nebulization ( SN), electrothermal vaporization ( ETV) and laser ablation ( LA) of dried micro- droplets as sample introduction systems for ICP- MS are compared for the determination of several radionuclides in digested biological tissue, nearshore sea-water and river water. Samples were subjected to a Ca-3( PO4)(2) co- precipitation preconcentration prior to analysis. Each introduction system possesses unique advantages and disadvantages. ETV accommodates samples having higher dissolved solids content; consequently, for SN and LA, sample concentrates require additional dilution by 50- and 10- fold, respectively. ETV and LA achieved similar sensitivities and limits of detection, the latter ranging from 0.017 to 0.029 pg ml(-1). Although SN provides the best precision (2% RSD versus 7 and 8% for ETV and LA, respectively), formation of uranium hydride can be reduced at least 100-fold using LA of dried micro- droplets of samples. The accuracy of the method was validated by determination of U and Th in NIST SRM 1566b Oyster Tissue, NRC CRM CASS- 4 Nearshore Seawater and SLRS- 4 Riverine Water and via spike recoveries for Pu.