The 'Analytical Network for Nanotech' is a European analytical infrastructure supporting the development of micro- and nano-technologies. High quality research requires comparability of results when analytical methodologies are supplied by different sources. This is a requirement of quality controlled industries, too. Inorganic contamination capabilities of the joint laboratory are Total Reflection X-Ray Fluorescence (TXRF) using Synchrotron Radiation (SR) or X-ray tubes, Vapor Phase Decomposition (VPD) and subsequent Graphite Furnace Atomic Absorption Spectroscopy (GF-AAS) or Inductively Coupled Plasma Mass Spectrometry (ICPMS), and Time of Flight Secondary Ion Mass Spectrometry (ToF SIMS). Discrepancies of results from different tools using TXRF for detection of metal contamination on silicon wafer surfaces were observed during different round robin using spin coated silicon wafers and deposited point like contamination. The results were validated using GF-AAS and ICPMS. The impact of the (reference) sample used for calibration on the evaluated measurement was confirmed. Furthermore, measurement geometries, substrate orientation and reliability of the angle of incidence are crucial for the comparability of the results of the TXRF systems.