288 Nuclear Instruments and Methods in Physics Research B3 (1984) 288-290 North-Holland, Amsterdam zyxwvutsrqp PIXJ3 AND NEUTRON ACTIVATION METHODS IN HUMAN HAIR MATERIAL ANALYSIS T. BjiDICA, C. CIORTEA, V. COJOCARU, M. IVASCU, A. PETROVICI, A. POPA, I. POPESCU, M. SALAGEAN and S. SPIRIDON Institute for Nuclear Physics and Engineering, P.O. Box MG 6, Bucharest, Romania In order to compare some of the nuclear methods in human hair material analysis, proton induced X-ray excitation and variant techniques of neutron activation analysis have been used. The elemental concentrations are compared with the IAEA-Vienna certified values. The efficiency and reliability of the methods used are briefly discussed. 1. Introduction As one of the final products of the human metabolic activities the human hair can be used to indicate the environmental pollution of toxic elements. Forensic, biological and clinical investigations are interested in the compoisition of hair as well. In this respect it is of great importance to improve the methods for the de- termination of microelement concentrations in hair. Furthermore, it is interesting to compare various nuclear analytical methods, from both the point of view of the reliability and the effort of the determination. The analysed material was the powdered human hair reference material, HH-1, distributed by IAEA-Vienna to laboratories interested in an intercomparison pro- gramme for trace and other elements [1,2]. Proton in- duced X-ray excitation (PIXE) and neutron activation analysis (NAA) were the work. 2. Experiment and results 2.1. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA PIXE methods used in the present The experimental apparatus was described previ- ously [3]. The irradiation chamber has a 0.2 mm beryl- lium window for X rays. The target was oriented at a 45” angle with respect to both the beam and detector directions. The beam passes through a collimator (+ = 2 mm) before reaching the target. For analysis we used proton beams of 3 MeV energy extracted from the tandem accelerator. The beam cur- rent was kept below 10 nA to maintain a count rate of about 250 counts/s, which implies negligible dead-time and pile-up corrections. X rays were detected with a Ge (80 mm* x 7 mm) detector with 180 eV resolution at 5.9 keV. The absolute concentrations of observed elements in the hair sample were determined by taking advantage of the internal standard [4-61. This calibration method implies doping the sample with a known amount of the standard element and relating the unknown concentra- tions to those of the standard element. The concentra- tion C, of an element present in the analysed sample can be estimated from: C,=R(Z,S)CsN,/Ns, where R is a calibration parameter and N is the number of counts for X-ray peaks. The indices Z and S refer to the analysed and standard elements, respectively. The 1CY21_ 20 30 40 50 7 L Fig. 1. Calibration parameter R(Z, Y) vs. the number Z of the element. 0168-583X/84/$03.00 Q Elsevier Science Publishers B.V (North-Holland Physics Publishing Division)