Analytical Sciences

Determination of Sixteen Elements and Arsenic Species in Brown, Polished and Milled Rice

Tomohiro NARUKAWA,* Eri MATSUMOTO,** Tsutomu NISHIMURA,** and Akiharu HIOKI*

*National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 3, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8563, Japan
** Japan Food Research Laboratories, 6-11-10 Nagayama, Tama, Tokyo 206-0025, Japan

The concentrations of 16 elements in 10 rice flour samples and the distribution of the elements in the rice grains from which the flour were made were determined by ICP-MS and ICP-OES after microwave-assisted digestion of the samples. Arsenic speciation analysis was carried out by HPLC-ICP-MS following heat-assisted extraction of the sample. The concentrations of inorganic As (As(III) and As(V)), monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA) and their distribution in the rice grains were determined. Portions of the brown rice were polished/milled to different degrees to yield milled off samples and polished rice samples. All samples were powdered and analyzed for 16 elements and for As species. The recoveries and mass balances for all elements in all samples showed good agreements with the starting materials. As(III), As(V), MMAA and DMAA were detected, and the sums of the concentrations of all species in the extract were 86 – 105% of the total As concentration in each case.

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