658 Nuclear Instruments and Methods in Physics Research B24/25 (1987) 658-661 North-Holland, Amsterdam TRACE ELEMENTS IN HUMAN NASAL CAVITY BONES * R.M. WHEELER, R.P. CHATURVEDI and J.S. ONELLO State Universit)"of New York, College at Cortland, Cortland, NY, USA V. VALKOVIC Institut Ruder Boskovic, Zagreb, Yugoslavia J. KRMPOTIC Faculty of Medicine, University of Zagreb, Zagreb, Yugoslavia In recent years, the use of synchrotron radiation for high-sensitivity trace multielement analysis has been well established. We have used a white X-ray beam from the Brookhaven National Synchrotron Light Source to analyze trace elements in nasal cavity bones from both males and females of various ages. Ca, Fe, Cu, Zn, Pb, and Sr ",'.ereroutinely identified. A 30×60/.tm photon beam was used to scan the samples to see variations in elemental concentrations. Results of our preliminary analysis as well as future plans to analyze more bone and other biomedical samples will be discussed. 1. Introduction Many elements found in trace amounts play im- portant functions in living organisms. In recent years, several multielemental techniques have been used to quantify the amounts of particular trace elements in biological materials. Krmpotic-Nemanic et al. have used proton induced X-ray excitation (PIXE) as well as X-ray fluorescence (XRF) to analyze the distribution of trace elements in various human nasal cavity bones [1]. In view of the fact that synchrotron radiation provides an intense source of linearly polarized photons, we have initiated a study of trace elements in nasal cavity bones using the National Synchrotron Light Source. 2. Procedure The experimental configuration is shown in fig. 1. This geometry takes advantage of the polarization of the incident X-rays so as to minimize background from both coherent and incoherent scattering in the target [2]. This is achieved by placing the detector at a 90 o angle with respect to the incident X-ray beam and in the plane of the orbiting electrons in the synchrotron. White radiation from the Light Source was collimated by a set of X by Y variable slits controlled by a Lecroy com- puter system. For this experiment the slits were kept fixed at 30 × 60 Fm, at this time a minimum configura- tion. To maintain the preferred geometry, a scanning stage with X, Y, and Z movement capability and a * Supported in part by NIH Synchrotron X-RAY Microprobe Facility, grant ~RR01838. 0168-583X/87/$03.50 © Elsevier Science Publishers B.V. (North-Holland Physics Publishing Division) fixed microscope coupled to a television camera allowed each specific target spot to be aligned in the correct orientation. The Si(Li) detector signal was amplified and the pulse heights analyzed with the same Lecroy system. The intensity of incident photons was measured with an in-line ionization chamber. To maintain a rea- sonable count rate the incident white light was passed through a 200 Fm aluminum filter, thus producing the spectrum illustrated in fig. 2. In this configuration, the roughly 25% concentration of calcium in bone still produced multiple sum peaks in the spectra. To reduce the calcium X-ray contribution, a fifteen mil Kapton filter was placed between the target and the detector. Resulting count rates were from 2000 to 5000/s. A typical 5 min X-ray spectrum of a concha nasalis infe- rior bone is shown in fig. 3. The elements identified were Ca, Fe, Cu, Zn, Pb, and Sr. Copper has the smallest concentration at roughly 4 ppm, which in this spectrum corresponds to about 2000 counts under the K, peak. The copper Kp peak is buried under the zinc K,~ peak. The areas under the labelled peaks in fig. 3 were determined using a nonlinear least squares fitting routine with fitting errors between 1 and 5%. A collection of autopsy specimens of fifty concha bones were obtained by one of us (J. Krmpotir). The samples included both males and females ranging be- tween 18 and 78 yr of age. A typical sample is shown mounted on a 35 mm slide in fig. 4. The bones varied from two to four centimeters long. Most of the bones surveyed were similar in shape and size to that shown in fig. 4. The bones were irregular in shape and clearly showed a high degree of porosity. Seventeen samples