and purify these elements are, chemistry. in most instances, based on fundamental classical These methods involve precipitation, coprecipitation, extraction, various forms of ion exchange, and are based on the classic oxidation-reduction proper-~ ties of the actinides and their similarity to the lanthanide series. The +3 state is characteristic of all the actinide elements, uranium to americium, and they are capable of being oxidized all the way to +6; in this respect, the actinides differ from the rare earths. From uranium to americium, the stability of the +6 state decreases regularly and there is a corresponding increase in the stability of the +3 state. At americium, the +3 state becomes the predomifMant one, and the only state known to exist for curium in aqueous solutions is the +3. The early analytical methods that were developed were used to separate and purify Pu from alpha emitters and beta~emitting fission products in fresh fission solutions. Subsequently, it became necessary to separate plutonium in trace quantities from a variety of environmentally derived matrices. Plutonium and the other transuranics were not conveniently in solution but in a variety of chemical and physical forms--some as colloids, some as complexes, and others in the form of highly refractory oxides fused with macro amounts of aluminum, iron, silica, etc. Further, in addition to removal of the artificial radionuclides, methods had to be developed to also remove the natural elements. The radiochemical procedures which were developed, therefore, employ the basic chemical techniques, but differ in a very special manner, due to the necessity of separation from environmental matrices. Usually, concentration may be required from large volumes and isolation from macro quantities of stable elements which differ from matrix to matrix and sample to sample. As a result, the procedures employed must be tailored to the specific matrix. Over the years, procedures have become simplified, consisting primarily of a concentration step, decontamination steps involving coprecipitation and ion exchange, and a final isolation for counting. Considerations in the evolution of concentration techniques are losses due to foaming, spattering, entrainment, formation of insoluble oxides, polymerization, etc. A successful procedure produces good yields, clean plates, high purity, with economy of materials and time and use of the least labor intensive methods. In the course of these operations, due to the large volumes and masses of the samples, management of the fumes and waste liquids produced must be considered. Lastly, for the more sensitive chemists, some of the odors produced are not exactly "Chanel No. 5." Much of the early plutonium chemistry, in 1943, at the University of Chicago Metallurgical Laboratory, was performed with less than 1,000 dpm of plutonium. Since this was all that was available, recovery techniques were devised for recycling the plutonium. Techniques employed then to isolate from a variety of experimental solutions were redox, coprecipitation, and hexone extractions, with great success. Later, in connection with nuclear weapons tests in the late 1940s, the transuranics, primarily neptunium and plutonium in the form of particulates, were recovered from inorganic and organic filter media, There were also many bioassay samples to be analyzed. These were invariably tracerfree. In the early 1950s, plant uptake of plutonium studies were also performed, Jacobson and Overstreet (1948), again tracer-free Animal studies at Lovelace and UC Davis and the TG-57 (1957 Safety Tests at NTS) and Roller Coaster, Major and Wessman (1964), plutonium safety tests made necessary the requirement for procedural development on large biological samples. HASL studies of worldwide fallout and the data produced on atmospheri c and surface distribution of the actinides led to the development of standarized procedures Harley (1957, 1972). Laboratories contributing to the development and application of transuranic procedures are the USERDA primes, such as LASL, LLL, Battelle, etc.; DOD units such as AFTAC, WPAFB, the now defunct NRDL, and LFE (Tracerlab). The procedures discussed herein apply to inorganic matrices such as soils; aqueous samples such as water, sea water, and liquid bioassay samples; and organics such as vegetation, animal, and filters. In addition to single element procedures, some discussion of sequential procedures is included. It is interesting to note that current work reported here also includes instrumental techniques which, in some instances, relieves the need for radiochemistry. It is also tronic that after years of development of tracer techniques, because of the desire to measure all transurani c nuclides in waste, there is now a need for reliable and accurate tracer-fre e techniques. DISSOLUTION AND CONCENTRATION TECHNIQUES ' The transuranics in environmental samples are usually low in activity and as a result, in order to obtain usable data, samples large in mass or volume must be taken. For example, the currently most abundant transuranic in soil is plutonium, with a typical average concentration of 0.02 dpm/g (0-20 cm), Hardy et al. (1972). Therefore, in order to recover the nuclide of interest, it is necessary to reduce the volume or mass to manageable amounts and assure its solubilization. Some samples such as soil require prior sieving and grinding. Organic matter must be decomposed. At an early stage, tracer must be added and equilibrated and lastly the final solution conditione d for the initial radiochemical separation and purification steps. Since these elements are not normally volatile, precautions in these Procedures are primarily mechanical and involve proper mixing to get a uniform sample and adjustment of temperatures and heating cycles to prevent mechanical losses. In the aqueous phases acidification 1s required to prevent polymerization or radtocoll oid formation and losses due to plating out prior to equilibration. The methods employed for volume or mass reduction in organic, inorganic, and aqueous samples are shown in Figure 1 and typical concentration steps are shown in Figure 2. SOILS Soil varies widely in physical and inorganic chemical composition and in the amount of organic material. A similar statement can be made about the form of 547