The Effect of Isotopic Composition on the Uncertainty of Routine Metal Mass Concentration Measurements in Ambient Air

Figure 1

Relative contributions to the standard uncertainty of the determination of metal mass concentration in ambient air, as part of the UK Heavy Metals Monitoring Network. This example shows a measurement with an overall expanded uncertainty at the 95% confidence interval of approximately 20%. The changing uncertainty contribution from the variation in the sample isotopic composition for the different metals measured by the “network” is indicated by the additional lines and labelling on the bottom bar.