ewe WCLASSIFTED ANALTTICAL DEVELOPMENT IN PROGRESS The Instruments Brarmh of the Health and Safety Laboratory hasi been developing a scintillation anti-coincidence counter for low larel bets measurements. This is designed around a solution phosphar con taining the active material in a volume of 5 to 10 ml. The prpble has been worked on by three groups; the 4nelytical Branch devdloping the method of obtaining the active material in solution, Profdssor Kallaann of NTU working on the development of the optimum phosphor, and the Instruments Branch working on the developat of ins pontation.. The chemical operations were largely devoted to the separation of T°? from the rediostrontius plue strontium carrier obtained if our normpal chemical procedures. It was desirable to extract the [* into an organic solvent that would also be a suitable solvent] for the fluors; such as terphenyl and the substituted anthracene. Initial experiments showed that certain complexing agents whifh gave organic soluble compounds with Y also acted the phosphor. as quenchew This was true of TIA (thenoyl trifluorcacetong). for Other reagents such as oxine gave poor extraction coefficients. Tributyl phosphate (TBP) has been used in the extraction of e due to the presence of nitric acid which also extracts into Br’ » earths from very strong nitric acid solution. The resultingforganic layers, however, were found to show very great quenching. is is It was not possible to wash out the HNO,, as the Tf activity removed in the process. oy Extracting YT from saturated ammonium nitrate solutions with s also PEP gave an organic layer which could be prepared as a good liquid phosphor. The pulse heights obtained are equivalent to phosphors prepared directly from TBP. Both 75% and 3% satureted amnariim mitrate solutions alse gave good extrection results, allow easier manipulation than if completely saturated. This technique should allow the ready messurement of very lw levels of Y°° ag carrier~free isotope, since the background of suc a scintéillation counter could be maintained at a low:level. This|proecedure may also be used for determination of Ce*** which is ong of the known non-fractionating fission products present in aged fallout debris. The second development is the use of a comparatives logarithmic absorption plot for isotope identification. In this pfethod, the logarithm of the relative activity of the unknown with Parious aluminum absorbers is plotted against the logarithm of the relative activity of a known isotape such as P**. The slope of the [resulting ert G 7 UNCLASSIFI=D 00131986 059 1057088