THE DETERMINATION OF LOW-LEVELS OF TC-99 IN ENVIRONMENTAL-SAMPLES BY INDUCTIVELY COUPLED PLASMA-MASS SPECTROMETRY

Tc-99 is produced in nuclear fission with a yield approximately comparable to that of Sr-90 and Cs-137, and it has been released into the environment during the last 40 years primarily as a result of nuclear fuel reprocessing. It is a beta emitter with a long half life, and its concentration in environmental materials is usually determined radiometrically. An alternative to radiometric methods which uses inductively coupled plasma-mass spectrometry and which is not subject therefore to interferences caused by ionising emissions from other radionuclides present in the sample is described. A chemical separation is carried out to concentrate Tc and to remove mass and matrix interferences. The application of the method to determine Tc concentrations in environmental materials from the Irish Sea is discussed. Limits of detection are comparable with those obtained with radiometric methods, but may potentially be significantly improved by developments in the instrumentation such as using electrothermal vaporisation. A further advantage of this technique is the rapid data acquisition (following chemical separation) of 1 min per sample compared with several hours for radiometric determinations.