Determination of uranium in human hair by acid digestion and FIAS-ICPMS

The content of heavy metals in human hair may serve as an indicator of occupational or environmental exposure to metal compounds. However, before such exposure can be determined, the level of the element in a normal population must be established. The concentration of uranium in human hair was measured by flow injection - inductively coupled plasma mass spectrometry (FIAS-ICPMS) after acid digestion of the hair samples. All hair samples were rinsed in order to remove external contamination prior to the digestion in a 2:1 solution of concentrated nitric acid and 30% hydrogen peroxide. The limit of detection of the method, for a 50 mg hair sample, was 0.015 mug/g, mainly due to the presence of impurities in the hydrogen peroxide. The range of uranium concentration in the initial test group was found to be 0.01-0.18 mug/g. The mean and median values of the entire study population were 0.062 and 0.050 mug U/g hair, respectively. Differences between the following sub-populations: male and female, smokers and non-smokers and people below and above 45 years of age were examined. The only statistically significant difference was found in the latter group (p = 0.03).