In 1906, Michael T. Sweet first developed the chromatographic method by using an adsorbant to separate pigments. Since that time, the technological advances in TLC and HPLC have brought about new definitions of purity in parallel with the advances. Radiopharmaceutical chemistry is especially dependent on the chromat ographic technique because of the relatively small amount of material in most radiopharmaceuticals-often so small that the usual physical methods of analytical chemistry cannot be used. As a result, this collection of papers represents the key to successful radiopharmaceutical...