Chromatographic isolation of the essential transition metals Fe, Cu and Zn from whole blood or blood serum for their subsequent isotopic analysis via MC-ICP-MS (multi-collector ICP – mass spectrometry). Comparison of results for a reference population with those for patient groups for evaluation of the diagnostic capabilities of isotopic analysis in this context. Targeted diseases include hemochromatosis, Crohn’s disease, Wilson’s disease and various types of liver diseases. Evaluation of the capabilities for blood spot analysis when using LA (laser ablation) as a means of sample introduction.