Determination of technetium-99 in environmental samples: A review

Due to the lack of a stable technetium isotope, and the high mobility and long half-life, 99Tc is considered to be one of the most important radionuclides in safety assessment of environmental radioactivity as well as nuclear waste management. 99Tc is also an important tracer for oceanographic research due to the high technetium solubility in seawater as TcO4−. A number of analytical methods, using chemical separation combined with radiometric and mass spectrometric measurement techniques, have been developed over the past decades for determination of 99Tc in different environmental samples. This article summarizes and compares recently reported chemical separation procedures and measurement methods for determination of 99Tc. Due to the extremely low concentration of 99Tc in environmental samples, the sample preparation, pre-concentration, chemical separation and purification for removal of the interferences for detection of 99Tc are the most important issues governing the accurate determination of 99Tc. These aspects are discussed in detail in this article. Meanwhile, the different measurement techniques for 99Tc are also compared with respect to advantages and drawbacks. Novel automated analytical methods for rapid determination of 99Tc using solid extraction or ion exchange chromatography for separation of 99Tc, employing flow injection or sequential injection approaches are also discussed.

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► The source term, physicochemical properties, environmental distribution and behaviour of 99Tc are presented.
► Various sample pre-treatment and pre-concentration techniques of technetium are discussed.
► Chemical separation and purification techniques for 99Tc in environmental samples are reviewed.
► Measurement techniques for 99Tc in environmental level and automated analytical methods are reviewed.
► The reported analytical methods of 99Tc are critically compared to provide overall information.