X‐ray fluorescence analysis of mercury in human hairs using a secondary target placed behind the sample

Abstract Mercury is a pollutant that poses a considerable health risk. The concentration of mercury in scalp hair can be used to estimate past mercury exposure. Methods such as atomic absorption spectrophotometry and inductively coupled plasma‐based techniques have been used to determine the concentrations of trace elements in scalp hairs; however, these analytical methods have several limitations, including the need for expensive equipment, complex sample preparation, and large samples of more than 100 hairs. Therefore, simpler and more cost‐effective methods are required. X‐ray fluorescence (XRF) spectroscopy is a simple and fast analytical method. To improve the sensitivity, we applied a secondary target method to enhance the XRF excitation and reduce the background. In conventional secondary target methods, the primary x‐rays irradiate a secondary target of a pure substance, and the sample is then irradiated with the fluorescent x‐rays from the secondary target. We placed high‐purity Y₂O₃ powder, which served as the secondary target, behind the hair samples. The XRF intensities of trace elements such as mercury and zinc in the hair were enhanced by applying the secondary target behind the hair.