HISTORICAL REVIEW OF TRANSURANIC ANALYTICAL METHODOLOGY Robert A. Wessman and Leon Leventhal LFE Environmental Analysis Laboratories Richmond, California ABSTRACT The methods used for the analysis of the transuranic elements neptunium, plutonium, americium, and curium are reviewed. Particular attention is given to those procedures suitable for low-level environmental and biological assess-— ment. The preparation of such samples, derived from a variety of sources and incorporated in different masses and volumes of soils, water, vegetation, and biological matrices, is described. A comprehensive discussion of matrix dissolution and equilibration techniques indicates that complete dissolution employing tracer techniques is to be preferred. Leaching of large soil samples is satisfactory for worldwide fallout. Individual and sequential separation and purification procedures, including precipitation, extraction, and ion exchange methods, are described. Sample preparation techniques for radiometric assay, such as stippling, evaporation, and plating, are reviewed. For both tracer and nuclide assay, electroplating provides the thin samples suitable for alpha pulse height analysis. Past and current counting methods for the transuranic alpha, beta, and gamma emitters are reviewed. INTRODUCTION Current interest in the transuranics (TU), particularly Np, Pu, Am, and Cm, stems from problems of potential or actual dissemination in the environment of reactor waste, fallout, and the progress on development of the breeder reactor. It also stems from such studies as the assessment of these elements at Enewetak and Bikini, studies of plutonium sites by the Nevada Applied Ecology Group, and a variety of plant and animal uptake studies. Recently, 24!Am, because of its growth from 2*!pu, has become a factor in the environment and interest in this isotope increased. Neptunium and curium as well as Am are expected to accumulate in radioactive waste from reprocessing plants and are also of interest. Although the history of the transuranic elements began a short time ago, with the advent of the nuclear age, the analytical methods employed to separate and 545