Elemental Imaging of Nail Sample by Confocal Micro-X-ray Fluorescence Analysis

Inductively coupled plasma mass-spectrometry has been commonly applied to determine the elemental concentrations of human fingernails. However, the obtained values are averaged quantitative values and elemental distributions in the plane and depth of nail samples have not been reported. In this study, we applied micro-X-ray fluorescence analysis equipped with a capillary optic for obtaining elemental distributions in the plane of a nail sample. The results showed that S and Ca were almost homogeneously distributed, while K and Zn were confirmed to be concentrated near the tip of the fingernail. Furthermore, confocal micro-X-ray fluorescence (CMXRF) analysis was employed nondestructively to obtain elemental depth distributions. As a result of analyzing the XRF intensity distribution of Ca after correcting for the absorption of the XRF inside the nail sample, the result suggesting that Ca distributed not only near the surface of the sample but also inside the nail was obtained.