DETERMINATION OF LONG-LIVED RADIONUCLIDES IN CONCRETE MATRIX BY LASER-ABLATION INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY

A laser ablation system using a Nd:YAG laser was coupled both to a qua drupole inductively coupled plasma (ICP) mass spectrometer and to a do uble-focusing sector field ICP mass spectrometer. Laser ablation induc tively coupled plasma mass spectrometry (LA-ICP-MS) was applied for th e determination of long-lived radionuclides in a concrete matrix. The investigated samples were two laboratory standards with a concrete mat rix, which we doped with different long-lived radionuclides (e.g. Tc-9 9, Th-232, U-233, Np-237) from the ng g(-1) to mu g g(-1) concentratio n range and an undoped concrete material (blank). Detection limits for long-lived radionuclides in the 10 ng g(-1) range are reached for LA- ICP-MS using the quadrupole mass spectrometer. With double-focusing se ctor field ICP-MS, the limits of detection are in general one order of magnitude lower and reach the sub ng g(-1) range for U-233 and Np-237 . A comparison of mass spectrometric results with those of neutron act ivation analysis on undoped concrete sample indicates that a semiquant itative determination of the concentrations of the minor and trace ele ments in the concrete matrix is possible with LA-ICP-MS without using a standard reference material. (C) 1997 Elsevier Science B.V.