Wheat flour (1567a) and peanut butter (2387) certified reference
materials (CRM) were obtained from the National Institute
of Standards and Technology (NIST, USA) for use in method validation
and quality control. Wheat flour contained most of our elements
of interest, while peanut butter was the most similar
matrix to peanut kernels. The digestion and analytical procedures
were also applied to peanut samples obtained from the plant
breeding program collaboratively run by the Peanut Company of
Australia (PCA), Grains Research and Development Corporation
(GRDC), and Queensland Department of Employment, Economic
Development and Innovation (DEEDI). The peanuts were grown
under non-limiting (nutrient- and water-replete) conditions in
2007/08, harvested and pre-processed (dried, de-hulled, and
graded) according to commercial practice, and then transported
to the University of New South Wales for analysis. The samples
comprised a set of 56 diverse genotypes grown at Kairi Research
Station in the Atherton Tablelands of north Queensland, and a set
of nine genotypes grown in five distinct environments located in
the central Burnett, south Burnett, and Atherton Tablelands production
areas.