DETERMINATION OF SOURCES OF LEAD IN TAP WATER BY INDUCTIVELY COUPLED PLASMA MASS-SPECTROMETRY (ICP-MS)

We measured the concentrations of Pb and its isotope ratios in coconmittantly obtained tap water and plumbing materials by inductively coupled mass spectrometry (ICP-MS). The Pb concentrations were determined by external calibration with Bi-209 as an internal standard. Isotope ratios were measured and mass discrimination corrected by normalization to NIST SRM-981 (common lead isotopic standard). Student's t-test was used to compare the isotopic ratios of Pb-206/Pb-207, Pb-206/Pb-208, and Pb-207/Pb-208 in the tap water with those in various plumbing materials. The comparisons revealed that the source of Pb in most of the tap water samples was derived from copper pipe or solder.