[en] Methods for measuring "2"3"8U, "2"3"2Th, and "2"1"0Pb in refined lead are presented. The "2"3"8U and "2"3"2Th concentrations are determined using isotope dilution inductively coupled plasma mass spectrometry after anion exchange column separation of dissolved lead samples. The "2"1"0Pb concentration is inferred through α-spectroscopy of a daughter isotope, "2"1"0Po, after precipitation separation of dissolved lead samples. Subsequent to the "2"1"0Po α-spectroscopy measurement, a method for evaluating "2"1"0Pb concentrations was developed via measurement of bremsstrahlung radiation from β-decay of a daughter isotope, "2"1"0Bi, using a 14-crystal array of high purity germanium detectors. Ten sources of refined lead were assayed and results are presented. (author)