High-sensitive determination of inorganic elements in spinach leaves by X-ray fluorescence analysis and its application to identification of their production area

An X-ray fluorescence (XRF) technique has been developed for analyses of trace elements in vegetables utilizing an energy-dispersive XRF spectrometer equipped with 3-dimensional polarization optics and secondary targets. Quantitative analyses were optimized with the calibration-curve method and the FP method based on the XRF intensity, normalized by that of Compton scattering. Various trace elements in spinach leaves grown at two major production sites, Gift] and Gunma prefectures, Japan, were successfully quantified by an easy sample-preparation technique over a wide concentration range from a few wt% (e.g. K and Ca) to sub-ppm (e.g. Cd and Ba) level. It was possible to clearly characterize the production locality of the spinach by statistical analysis of the trace characteristic elements, such as Ca, Zn, Br, Rb, Mo, and Ba. In addition, it was found that this XRF technique is suitable for rapid and easy screening analysis of Cd in vegetables at their production sites for the environmental regulation requirements.