The provision of reference values to an Australian interlaboratory study of themeasurement of elements in wheat flour
National Measurement Institute, Sydney, Australia
The National Measurement Institute conducts regular interlaboratory (proficiency) testing studies for Australian and international testing laboratories as part of a broad program of metrology in chemistry. These studies target areas of chemical testing that are of high public significance (eg trade, environment and public health). An objective of these studies is to provide testing laboratories with a tool to assess the accuracy of their test results and hence the effectiveness of their test methods and quality assurance programs. A second objective is to provide traceability to the Australian measurement infrastructure.
In a recent study involving the analysis of 24 elements in a wheat flour matrix, the NMI provided reference values for a selection of ten of the full list of elements. These reference values were assigned using primary analytical techniques, providing traceability in the analysis of these elements through the Australian NMI to international systems of measurement, allowing participants to directly compare their measurement with the assigned reference value, and gauge their measurement capability. These reference methods were also used to measure a range of CRMs, and have been benchmarked to the primary methods used in other NMIs in other countries.
This paper describes the development of high accuracy primary methods of analysis for ten trace elements in wheat flour and their use to provide reference values for a proficiency testing scheme.