This International Standard specifies chemical methods for the collection of iron and/or nickel from the surface of silicon-wafer working reference materials by the vapour-phase decomposition method or the direct acid droplet decomposition method. NOTE The determination of the elements collected may be carried out by graphite-furnace atomic-absorption spectroscopy or inductively coupled plasma mass spectrometry instead of by total-reflection X-ray fluorescence spectroscopy. This International Standard applies to iron and/or nickel atomic surface densities from 6 × 109 atoms/cm2 to 5 × 1011 atoms/cm2.