Preliminary assessment of homogeneity of new candidate agricultural/food reference materials

Summary In an effort to bring to the analytical community new natural matrix reference materials (RM's) for elemental composition quality control, ten new agricultural/food candidate reference materials prepared previously, were characterized for homogeneity. The materials include bovine muscle powder, whole egg powder, corn bran, microcrystalline cellulose, wheat gluten, whole milk powder, corn starch and three wheat flours representing a wide range of matrix types and elemental composition. Characterization was for up to some twenty five major, minor, trace and ultratrace elements of nutritional, toxicological and environmental significance. Solid sampling electrothermal atomic absorption spectrometry was applied to the determination of copper and lead in sub-milligram subsamples. A variety of other analytical techniques via an interlaboratory cooperative effort was used to determine many other elements in 100–2000 mg subsample sizes. Good material homogeneity was observed for virtually all materials and analytes with the exception of Cr and Pb in limited instances. The materials were thus deemed suitable for detailed characterization of elemental concentration to lead to recommended values and to bring these biological products to reference material status.