Researchers in Canada have developed a method for the rapid ultra-trace measurement of strontium 90 (⁹⁰Sr) in environmental samples.

⁹⁰Sr is a by-product of the fission of uranium and plutonium in nuclear reactors and nuclear weapons, with a half-life of 29 years. It was widely dispersed into the environment during nuclear weapons testing in the 1950s and '60s. It is chemically similar to calcium so it accumulates in bone and blood-forming tissue. Exposure to ⁹⁰Sr may be linked to certain cancers.

Patricia Grinberg and coworkers at the Institute for National Measurements Standards in Ottawa used ICPMS combined with electrothermal vaporisation and dynamic reaction cell technology to measure ⁹⁰Sr concentrations as low as 3.5 picograms per gram. The method was tested by measuring natural Sr in marine sediments, river water and biological material and the recovery of ⁹⁰Sr spikes added to the samples.

'The determination of ⁹⁰Sr is non-trivial both as a consequence of its extremely low concentration levels and because it suffers from interferences, frequently necessitating laborious separation procedures, which can cause contamination and increase the analysis time' said Grinberg.

Grinberg's method takes advantage of the ability of electrothermal vaporisation systems to use thermal programming to selectively remove interferences and simplify sample preparation procedures.

The work is part of a project financed by the Chemical Radiological and Nuclear Research Technology Initiative (CRTI) in Canada on the development of new technologies for the rapid detection and identification of radionuclides.

'Radionuclides have traditionally been measured using radiometric techniques which are not ideally suited to rapid and/or accurate determination,' said Grinberg. 'Rapid determination is crucial in the event of a nuclear or radiological accident so as to assess and minimize adverse health, economic and environmental effects,' she continued.

Joanna Stevens