Certification of Standard Reference Material® 1992 / ERM®-FD305 Zeta Potential Colloidal Silica (Nominal Mass Fraction 0.15 %)
Yannic Ramaye, Vikram Kestens, J. Charoud-Got, S. Mazoua, G. Auclair, Tae Joon Cho, Blaza Toman, Vincent A. Hackley, T. Linsinger
This report describes the production of SRM 1992/ERM-FD305, silica particles suspended in a borate buffer, certified for electrophoretic mobility and zeta potential by electrophoretic light scattering (ELS). This material was produced following ISO 17034:2016 and is certified in accordance with ISO Guide 35:2017. The certified reference material (CRM) was jointly produced by the Directorate F - Health, Consumers and Reference Materials of the European Commissions Joint Research Centre (JRC) in Geel (Belgium) and the US National Institute of Standards and Technology (NIST), Gaithersburg (USA). The CRM was produced from a buffer-modified and diluted commercial colloidal silica slurry. Between-ampoule homogeneity was quantified and stability during dispatch and storage were assessed in accordance with ISO Guide 35:2017. The minimum sample intake for the ELS method was determined from the results and information provided by the laboratories that participated in the interlaboratory comparison (ILC) exercise. The material was charactized by an interlaboratory comparison between laboratories of demonstrated competence and adhering to ISO/IEC 17025. Technically invalid results were removed but no outlier was eliminated solely on statistical grounds. Uncertainties of the certified values were calculated in accordance with the Guide to the Expression of Uncertainty in Measurement (GUM) and include uncertainties related to possible inhomogeneity, instability and characterization. The material is intended for quality control and assessment of method performance. The CRM is available in 5 mL pre-scored amber glass ampoules each containing approximately 5 mL of suspension.