Abstract
Stable isotopes of iron, zinc, and copper can be used singly and in combination as tracers of mineral metabolism in human subjects. A mass spectrometric method of analysis that uses chelation of these metals with tetraphenylporphyrin was developed. Absorption can be determined by measuring isotope appearance in feces after a single pulse dose. The method is satisfactory for 54Fe, 67Zn, and 65Cu. Detection of 57Fe and 70Zn in feces is not very reliable.