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High resolution inductively coupled plasma mass spectrometry for the trace determination of plutonium isotopes and isotope ratios in environmental samples

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A high resolution inductively coupled plasma mass spectrometric (HR-ICP-MS) method for the determination of plutonium isotopes and the 240Pu/239Pu isotope ratio utilising ultrasonic nebulisation was developed. Total plutonium concentrations (239+240pu) measured in environmental samples by this HR-ICP-MS method were in good agreement with data obtained from α-spectrometry. Quantification was performed by both external calibration and isotope dilution and the best agreement was found by applying isotope dilution. Detection limits of 5, 1 and 1 fg ml-1 were found for 239Pu, 240Pu and 242Pu, respectively. These represent total amounts of 50, 10 and 10 fg or 0.1, 0.08 and 0.002 mBq of the three isotopes in a 10 ml sample volume. The precision (RSD) on the measurement of the 240Pu/239Pu ratio in environmental samples was approximately 2%, which is close to the theoretical precision (Poisson statistics). The influence of dwell time, number of sweeps and sample uptake rate on the measurement precision of the 240Pu/239Pu isotope ratio was investigated and the parameters were optimised using a 23 experimental design (a central composite design followed by a ridge analysis). The accuracy of the isotope ratio measurement was evaluated by comparing results from this HR-ICP-MS method with results from high resolution α-spectrometry and spectral deconvolution. Good agreement was found between the two techniques.

OriginalsprogEngelsk
TidsskriftJournal of Analytical Atomic Spectrometry
Vol/bind13
Udgave nummer12
Sider (fra-til)1321-1326
Antal sider6
ISSN0267-9477
DOI
StatusUdgivet - 1 jan. 1998

ID: 199499009