VALIDATION OF THE ANALYTICAL LINEARITY AND MASS DISCRIMINATION CORRECTION MODEL EXHIBITED BY A MULTIPLE COLLECTOR INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETER BY MEANS OF A SET OF SYNTHETIC URANIUM ISOTOPE MIXTURES

A set of commercially available synthetically prepared mixtures of ura nium isotopes (IRMM 072) were used to assess the linearity and mass di scrimination exhibited by a multiple collector ICP-MS instrument. Meas urements of eight uranium isotopic reference materials with U-233:U-23 5 isotope abundance ratios ranging from 1 to 0.01 were made. Linear, p ower law and exponential relationships between instrumental mass discr imination and mass difference were evaluated. The power law and expone ntial function resulted in the best correction. The corrected isotope abundance ratios for U-233:U-235 and U-233:U-238 did not differ signif icantly from the certified values at the 3 x 10(-4) level.