Use of 113Cd and 207Pb Nuclear Magnetic Resonance Spectroscopy and Flame Atomic Absorption Spectroscopy to Study the Binding of Toxic and Carcinogenic Metals to Calcium Proteins

Flame atomic absorption (FAA) spectroscopy was used to quantitate levels of cadmium (Cd) and lead (Pb) in four mainstream calcium supplements, with ranges of 0.04-0.09 mug/g tablet for Cd and 0.670-.88 mug/g tablet for Pb being observed. Following this, Cd-113 and Pb-207 nuclear magnetic resonance (NMR) spectroscopy studies were undertaken to observe competitive binding of both metals in three different calcium-binding model systems: calcein (a chelator), casein (Ca2+-rich milk protein), and the calcium-binding protein (CBP) (highly specific for Ca2+). The rationale for this study was to ascertain whether or not the presence of lead and Cd in dietary supplements was to such a degree as to warrant concern by users of the products.