Neutron activation analysis applied to the determination of trace elements in human nails

There is a considerable interest in the determination of trace elements in human nails in order to use this tissue as a monitor of nutritional and healthy status of individuals, of occupational exposure diseases and of the environmental contamination. In this work, instrumental neutron activation analysis was applied to determine trace elements in finger nail clippings to make comparisons between the elemental concentrations obtained in nails from healthy individuals of a control group and those from cystic fibrosis (CF) patients. Firstly, a protocol for sample collection and preparation for analysis was established. Finger and toe nail samples from CF patients were collected at the Instituto da Crianca of Medicine School, University of Sao Paulo, SP. The nail samples from control group were collected from healthy adults and from children living in Sao Paulo city, SP. These samples were cleaned by stirring them witha a diluted Triton X100 solution and then by washing with distilled water and acetone. The analytical procedure consisted of irradiation nail samples and elemental standards in the IEA-R1m nuclear reactor under thermal neutro flux of about 1012 n cm-2 s-1, for short and long period irradiations. The activities of the radionuclides were measured using a gamma-ray spectrometer comprising an hyperpure Ge detector and associated electronic system. The biological reference materials Bovine Liver 1577b and Oyster Tissue 1566a, both from National Institute of Standards and Technology, USA were analysed in order to evaluate the accuracy and precision of the results. The analysis of variance (ANOVA) and F-test at the significance level of 5% were used to make a comparison between the sets of results obtained in this work. In the comparison of the results obtained for finger and toe nails from CF patients, the Br concentrations were higher in finger nails that those obtained for toe nails. For the control group of children, the finger nails presented different levels of Br, Cl, Cr, Cu and Fe from those obtained for the toe nails and in the case of control group of adults, significant differences were obtained for Cr, Cl, Cu, K, Mg and Se. Concentrations of elements found in nails from control group of children were significantly different from those obtained for CF group for some elements. These two groups of individuals presented different concentrations of Br and Cr for toe nails and of Cl, Cr, K and Na for finger nails. The highest levels obtained for Cl and Na in nails from CF patients indicate the viability of using these analysis in the diagnosis of this disease. Comparisons between the results of nail samples from control group of children with those obtained for adults also indicated significant differences. Besides, the levels of the elements obtained in this work for nail samples from CF and control groups are within the range values presented in the literature. The elemental concentrations obtained in the analysis of hair samples indicated a good correlation with those obtained for nail samples. (author)