The certification of the mass fractions of total arsenic, dimethylarsinic acid and the sum of arsenite and arsenate in rice : certified reference material ERM®-BC211

This report describes the production of ERM-BC211, a powdered rice material certified for the mass fractions of total arsenic, dimethylarsinic acid and the sum of arsenite and arsenate. The material has been produced following ISO Guide 34:2009 [1]. The starting material, which had been checked for its arsenic species was purchased and supplied by the University of Aberdeen. The rice was milled, sieved, dried, homogenised, filled in vials and sterilised. Between unit-inhomogeneity was quantified and stability during dispatch and storage was assessed in accordance with ISO Guide 35:2006 [1]. Within-unit inhomogeneity was quantified to determine the minimum sample intake. The material was characterised by an intercomparison among 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 estimated in compliance with ISO/IEC Guide 98-3, Guide to the Expression of Uncertainty in Measurement (GUM) [1] and they include contributions from possible between-unit inhomogeneity, instability and characterisation. The material is intended for quality control and assessment of method performance. Moreover, it can be used fvalidation purposes and trueness determination. The CRM is available in glass bottles containing 10 g of dried rice powder closed under argon atmosphere. The minimum amount of sample to be used for total arsenic and dimethylarsinic acid is 50 mg. The minimum amount of sample to be used for the sum of arsenite and arsenate is 100 mg. The CRM has been accepted as European Reference Material (ERM) after peer evaluation by the partners of the European Reference Materials consortium.