Abstract: The zirconium/hafnium ratios of zircons are determined using proton induced X-ray emission. Submilligram samples, imbedded in a starch layer and deposited on a 50 μg/cm2 polystyrene carrier, are irradiated for 1020 min with a 5 nA beam of 3.7 MeV protons, while the Hf-Lβ and Zr-Kα X-rays are counted with a Si(Li) detector. The standard deviation per analysis is in the 36 % range. Only few interferences are possible. To eliminate errors due to absorption effects the zircon layer thickness should be above 40 μm or reproducibly thin samples should be employed. Measuring the Hf-Lβ/Hf-Lα ratio for samples and standards might provide a practical check for the absence of absorption errors. The sensitivity is so favourable that, in practice, the minimal sample size is only limited by the minimal amount that can be handled properly.

Abstract: Repeated intraperitoneal injections of lead acetate in rats caused a calcification of the skin of the abdomen near the site of the injections. In the lead-induced calcifications, electron dense collagen bundles could be observed. On the surface of the collagen fibrils, needle-like crystals were visible. With energy-dispersive X-ray analysis, phosphorus, calcium and lead were detected in the electron dense collagen bundles. X-ray maps of the P-Kα, Ca-Kα, and Pb-Lα plus Pb-Lβ lines showed an equivalent distribution along the collagen fibrils for phosphorus and calcium. The occurrence of the most electron dense areas in the STEM-image was comparable to the lead distribution. A good correlation existed between the structural and the elemental images of the same area. Although the medicinal use of preparations containing lead is no longer recommended, some are still prescribed. From our results we can conclude that they should not be applied to injured or inflamed skin.