Determination of plutonium in seawater using co-precipitation and inductively coupled plasma mass spectrometry with ultrasonic nebulisation

A flow injection-inductively coupled plasma-mass spectrometric (FI-ICP-MS) procedure, utilising ultrasonic nebulisation with membrane desolvation (USN/MD), has been developed for the determination of plutonium (Pu) in seawater at fg l(-1) concentration levels: Seawater samples (11), after filtration, were subjected to co-precipitation with NdF3, followed by ion exchange to enrich Pu and to reject seawater matrix ions and co-existing uranium. The seawater concentrate (1.0 ml) was then analysed by FI-ICP-MS. The limit of detection for Pu-239 in seawater based on an enrichment factor of 1000 was 5 fg l(-1), and precision at the 0.80 pg l(-1) level was 12% RSD. Accuracy was verified via recovery experiments, and by comparing survey data for the Irish Sea with that derived by standard methodology based on co-precipitation and ol-spectrometry. Concentrations for dissolved Pu-239 and Pu-240 in the Irish Sea were in the range of 0.267-0.941 pg l(-1) (0.614-2.164 mBq l(-1)) and 0.0510.196 pg l(-1) (0.428-1.646 mBq l(-1)), respectively. (C) 1998 Elsevier Science B.V. All rights reserved.