Impurity profiles of selected samples are determined by neutron activation analysis. After irradiation and cleaning with a mixture of hydrochloric and nitric acid a layer of 20 μm was etched with hydrofluoric and nitric acid. In the layer 0.5 ng/cm² Cu and 3 ng/cm² Fe were found. In cutted slides of zonefloated silicon we found a deep profile expressed by the equation c=c_o·exp-(x/a)², c_o=2 ppm, a=190 μm.