Feasibility study on the development of an Indonesian reference material for determination of nutrient in milk

Certified reference materials (CRMs) provide measurements of quality and metrological traceability related to the International System of Units (SI). In this study, a candidate reference material (RM) for determination of nutrients (Ca, Cu and Zn) in milk powder has been developed and will become the first Indonesian milk CRM. Several analytical parameters for the preparation and measurement of the candidate RM have been optimized based on a microwave acid digestion and ICP-MS method. A 25 kGy60Co dosage of gamma radiation has been applied for the sterilization of the sample prior to storage at room temperature. The CRM BCR-BD151 Skimmed Milk Powder from European Reference Material (ERM) and CRM7512a Trace Elements in Milk Powder from National Metrology Institute of Japan (NMIJ) were used to validate the measurement method and to control the measurement quality. The results showed that, according to ISO/IEC Guide 35:2006, the prepared milk was found to be sufficiently homogenous as a matrix of nutrient reference materials with % inhomogeneity less than 2% for Ca, Cu, and Zn.