A sample preparation has been developed for NanoSIMS 50 analysis of biological samples, that does not require thin sectioning. The embedded sample was surfaced by a diamond knife and directly analyzed. This sample preparation technique is well adapted for the investigation of diffusible elements and an example of iodine-containing water-soluble molecule localization in human hair is shown. We compared the results with conventional thin wet sectioning. (c) 2006 Elsevier B.V. All rights reserved.