Chemical challenges in the study of natural radioactive chains

Natural radioactivity was first confirmed by chemical means, and for many y ears it was the only known form of radioactivity. Chemical techniques remai n necessary for obtaining samples of series components on which detailed st udies can be made. These techniques must contend with features peculiar to or emphasized in the natural decay series-low specific activities of long-l ived parents and trace quantities of short-lived intermediates, interferenc es from carriers (isotopic or non-isotopic), and rapid growth of impurities in initially pure fractions. Examples of each of these features (challenge s) are given.