Determination of Pb in Biological Samples by Graphite Furnace Atomic Absorption Spectrophotometry. An Exercise in Common Interferences and Fundamental Practices in Trace Element Determination

This laboratory experiment demonstrates the use of graphite furnace atomic absorption spectrophotometry (GFAAS) for the determination of trace levels of Pb in bovine muscle or liver samples. The major emphasis of the experiment is to explore common interferences, first by investigating the impact of molecular spectral absorption interferences on a real-world sample, then demonstrating the susceptibility of GFAAS to chemical–physical matrix interferences. The combination of D2 arc background correction and calibration by standard additions is sufficient to reduce the magnitude of the interferences and obtain accurate Pb recoveries in these samples. This experiment also presents options for undergraduate chemistry majors to explore a number of other collateral issues related to the preparation of solid, biological samples for trace-level elemental determinations including sample decomposition, important figures of merit, and aspects of quality assurance in chemical measurements.