DETERMINATION OF PLUTONIUM IN SEAWATER USING COPRECIPITATION AND INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY WITH ULTRASONIC NEBULIZATION

A flow injection-inductively coupled plasma-mass spectrometric (FI-ICP -MS) procedure, utilising ultrasonic nebulisation with membrane desolv ation (USN/MD), has been developed for the determination of plutonium (Pu) in seawater at fg l(-1) concentration levels: Seawater samples (1 1), after filtration, were subjected to co-precipitation with NdF3, fo llowed by ion exchange to enrich Pu and to reject seawater matrix ions and co-existing uranium. The seawater concentrate (1.0 ml) was then a nalysed by FI-ICP-MS. The limit of detection for Pu-239 in seawater ba sed on an enrichment factor of 1000 was 5 fg l(-1), and precision at t he 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-spec trometry. 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) 199 8 Elsevier Science B.V. All rights reserved.