The certification of the equivalent spherical diameters of silica nanoparticles in aqueous solution, ERM- FD102 : certification report

This report describes the production of ERM®-FD102, silica nanoparticles in an aqueous solution certified for different equivalent diameters. The material was produced following ISO Guide 34:2009. The certified reference material (CRM), which has been produced by the Institute for Reference Materials and Measurements (IRMM) of the European Commission's Joint Research Centre (JRC), is a mixture of two monomodal populations of silica nanoparticles with distinct nominal particle sizes of 20 nm and 80 nm. These nominally 20 nm and 80 nm particle populations are further referred to as size class A and size class B, respectively. The CRM was prepared from two commercially available silica sols, moderately diluted in an aqueous solution and bottled in 10 mL pre-scored amber glass ampoules. Between unit-homogeneity was quantified and stability during dispatch and storage were assessed in accordance with ISO Guide 35:2006. The minimum sample intake for the different methods was determined from the results and information provided by the laboratories that participated in the interlaboratory comparison (ILC) exercises of the characterisation study. The material was characterised, for size classes A and B, by an intercomparison amongst laboratories of demonstrated competence and adhering to ISO/IEC 17025. Technically invalid results were removed but no outlier was eliminated on statistical grounds only. Uncertainties of the certified values were calculated in accordance with the Guide to the Expression of Uncertainty in Measurement (GUM) and include uncertainty contributions related to possible inhomogeneity and instability and to characterisation. The material is intended for quality control and assessment of method performance. As any reference material, it can also be used for control charts or validation studies. In addition, ERM-FD102 can be used for calibration of electron microscopy methods. The CRM is available in amber glass ampoules containing about 9 mL of suspension. The CRM was accepted as European Reference Material (ERM®) after peer evaluation by the partners of the European Reference Materials consortium.