CERTIFYING THE CHEMICAL-COMPOSITION OF A BIOLOGICAL-MATERIAL - A CASE-STUDY

A worldwide laboratory intercomparison was organized by the Internatio nal Atomic Energy Agency's Analytical Quality Control Services (AQCS) involving the determination of trace elements in plant materials used for human consumption. The National Institute of Standard and Technolo gy (NIST) Standard Reference Materials Program donated 5 kg of spinach designated for the production of the future Standard Reference Materi al SRM 1570a to this intercomparison; the AQCS provided a similar amou nt of cabbage. For the study, 150 units of each material were distribu ted and 114 laboratories reported results on both materials to AQCS. T he results for the spinach, encompassing more than forty elements, hav e been compiled and evaluated; estimates of the elemental concentratio ns were made based on statistical evaluations, principles of analytica l procedures and the laboratory performance indicated by the results o n the cabbage material. Satisfactory estimates were obtained for 27 el ements. Comparison with IAEA laboratory and NIST reference data did no t reveal any significant bias that might have been introduced by the i ntercomparison approach or its evaluation.