Isotopic analysis of the metabolically relevant transition metals Cu, Fe and Zn in human blood from vegetarians and omnivores using multi-collector ICP-mass spectrometry

Multi-collector ICP-mass spectrometry (MC-ICP-MS) was used for the isotopic analysis of Cu, Fe and Zn, isolated from human whole blood. For chromatographic isolation of these elements, the method first described by Marechal, Telouk and Albarede (Chem. Geol., 1999, 156, 251-273) and relying on the use of AG MP-1 strong anion exchange resin was further tailored and subsequently validated. It was shown that all three target elements could be obtained in pure form and with quantitative recovery from Seronorm whole blood reference material. MC-ICP-MS isotope ratio measurement conditions were optimized so as to avoid the influence of spectral overlap and the capabilities of several methods to correct for instrumental mass discrimination were compared. The method developed was then applied to a set of whole blood samples from supposedly healthy volunteers (reference population). For Fe, the by now well-known difference in isotopic composition between blood from male and female individuals was confirmed. The isotopic composition of Zn in whole blood was assessed to be governed by the diet as a significant difference could be established between blood from vegetarians and from omnivores, respectively. For the isotopic composition of Cu, interpretation of the results is more challenging, as neither gender, nor diet seems to have a significant influence, but the combined influence of both factors may show an effect.