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, Tc-99 is considered to be one of the most important radionuclides in safety assessment of environmental radioactivity as well as nuclear waste management. Tc-99 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 Tc-99 in different environmental samples. This article summarizes and compares recently reported chemical separation procedures and measurement methods for determination of Tc-99. Due to the extremely low concentration of Tc-99 in environmental samples, the sample preparation, pre-concentration, chemical separation and purification for removal of the interferences for detection of Tc-99 are the most important issues governing the accurate determination of Tc-99. These aspects are discussed in detail in this article. Meanwhile, the different measurement techniques for Tc-99 are also compared with respect to advantages and drawbacks. Novel automated analytical methods for rapid determination of Tc-99 using solid extraction or ion exchange chromatography for separation of Tc-99, employing flow injection or sequential injection approaches are also discussed. (C) 2011 Elsevier B.V. All rights reserved.