Trace elemental analysis of polished rice was performed using an X-ray fluorescence spectrometer equipped with 3D polarized optics system in order to characterize the geographical origins. Using the XRF spectrometer, trace elements in polished rice were determined in a total of 10 countries: eight Asian countries (Japan, China, Malaysia, Bangladesh, Myanmar, Cambodia, Sri Lanka, and Thailand), plus the United States and Australia. By using Ti, Ge, and Zr as secondary targets, 11 elements (P, S, Cl, K, Ca, Mn, Fe, Cu, Zn, Br and Rb) were detected in a 15-minute measurement, and 7 of these elements (P, K, Mn, Fe, Cu, Zn, and Rb) were quantified by the calibration curve method. Multivariate analysis of the compositions of these seven elements in combination with the stable isotope ratios δ13C, δ15N, and δ18O revealed more geographical characteristics of Asian rice than when the elemental compositions or the isotope ratios was used for multivariate analysis. In particular, P concentration and δ15N values were effective in discriminating between geographically close Japan and China. Furthermore, a comparison between Japanese conventional rice and organically grown rice with a clear cultivation history showed that Rb concentration and δ15N value were greatly affected by the cultivation method.
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