ACCURATE AND PRECISE MEASUREMENTS OF LEAD IN BONE USING ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY WITH ZEEMAN-EFFECT BACKGROUND CORRECTION

A simple method for measuring trace levels (mu g g(-1)) of Pb in bone by electrothermal atomic absorption spectrometry (ETAAS) is described, ETAAS instrumentation equipped with a transverse Zeeman-effect backgr ound correction system was used to investigate the effects of bone mat rix on Pb atomization, It is shown that Pb can be accurately measured with good precision using aqueous Pb standards containing NH4PO4 modif ier and Ca(NO3)(2). Alternatively, Mg(NO3)(2) works as well as Ca(NO3) (2). For rapid and contamination-free sample preparation, bone was dig ested in concentrated HNO3 nsing a closed-vessel microwave digestion s ystem. This approach was compared with digestion at room temperature o ver 48 h. The detection limit (3s) is 0.6 mu g g(-1) dry mass. Typical day-to-day precision is <5%. Method accuracy is established as better than 1% using NIST SRM 1400 Bone Ash and SRM 1486 Bone Meal, which ar e the only reference materials me have found for bone-Pb measurements. The method was used to analyse various bone specimens (e.g., tibia, f emur, rib and skull) from Pb-dosed animals, Results indicate that Pb i s heterogeneously distributed within bone.