PROTOCOL FOR ISOTOPE-DILUTION USING INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY (ICP-MS) FOR THE DETERMINATION OF INORGANIC ELEMENTS

The Comite Consultatif pour la Quantite de Matiere (CCQM) endeavours t o identify and carry out key activities with the objective of facilita ting world-wide comparability and traceability of chemical measurement s. Towards this goal, the CCQM has identified comparisons to be carrie d out using candidate primary methods of chemical analysis. One such m ethod is isotope dilution mass spectrometry. In the first comparison c arried out by the CCQM (Study I), the concentrations of various inorga nic elements were determined in water solutions using IDMS. The result s did not meet the target level of 1% maximum relative deviation from the reference values of the unknowns. It was concluded that more guida nce was necessary on the execution of the IDMS method and that a detai led protocol should be developed. Participants would use inductively c oupled plasma (ICP) as the ionization source. Here we present the prot ocol developed for use by CCQM participants in the next comparison (St udy III) on the determination of the concentration of lead in water us ing the IDMS method with an inductively coupled plasma-mass spectromet er.