RADIOISOTOPES
Online ISSN : 1884-4111
Print ISSN : 0033-8303
ISSN-L : 0033-8303
Direct Determination of Uranium in Rainwater by High Resolution ICP-MS with an Ultrasonic Nebulizer
Akito TSUMURAReiko OKAMOTOYuu-ichi TAKAKUShin-ichi YAMASAKI
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JOURNAL FREE ACCESS

1995 Volume 44 Issue 2 Pages 85-92

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Abstract

A direct method was developed for the determination of ultratrace U in rainwater by high resolution ICP-MS. Using the ultrasonic nebulizer sample introduction system, we were able to reach an ultimate detection limit of 0.06 pg/l for 235U based on three times the standard deviation of the blank fluctuation.
The proposed method has excellent sensitivity and it was possible to measure ultrat race levels of U and 235U to 238U ratio in all rainwater samples directly with acceptable speed (5 min/sample) and precision (RSD 5%) . The range of concentration of U in 23 rainwater samples collected at Tsukuba and Tokyo in 1992-1993 was 0.56 ng/l -14.2 ng/l with an arithmetic mean of 3.3 ng/l and a weighed mean of 1.7 ng/l.
The isotope ratios of 235U : 238U for the samples were in good agreement with the natural abundance of these nuclides.
It was found that the relation between the intensity of rainfall and uranium concentration shows a negative correlation significant at the 1 % level of significance (r=0.643**) . The data approximately follow a hyperbolic curve, with U concentration decreasing as the precipitation rate increases.

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© Japan Radioisotope Association
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