Orthodox uncertainty budgeting for high accuracy measurements by isotope dilution inductively coupled plasma-mass spectrometry

A full uncertainty budget for the analysis of copper in dilute nitric acid solution by isotope dilution ICP-MS has been formulated and described. The budget was dominated by the contribution of the standard uncertainty of the measured isotope amount ratios of the sample blend and the blend used for mass bias correction. The contribution from other components such as weighing, isotopic composition, standard solution concentration, and dilution factors were not very significant. The accuracy of the method was demonstrated by the analysis of NIST SRM 3114 copper solution.