DETERMINATION OF NEPTUNIUM-237 IN HUMAN URINE. KY-429.

A method has been developed for determining nept'unium-257 in human uTine specimens» The urine is acidified^ then concentrated by evaporation. Uraniua is removed by a double lanthanura fluoride precipitation using ferrous aamonium sulfate and hydroxylamine hydrochloride as reducing agents. Separation from plutoniua is effected by a theaoyltrifluoroacetone extraction using potassium iMide-hydr^ine or potassium iodide-hydroxylamine to reduce plutonium to Pu"^ and neptianiua to Ip *. The trivalent plutonium, is not extracted by TTA. IJeptuniun is stripped from the TTA ¥ith HCl and electrodeposited on stainless steel discs from an acid-chloride electrolyte. Recovery of a 200 alpha cpm Ip̂ ®"̂ spike is 87fo ± Q.% JEx and of a 1 alpha cpm Ip̂ ®*̂ spike is Sofs ± 26fo LEx. DETEBIClATIOl OF IIEFTlfflIIM-557 IE WMMl URISE The purpose of this investigation was to develop a urinalysis procedure to detect, ¥ith reasonable accuracy^ 1 alpha cpm lip̂ ®"̂ in urine speciciens. In the initial phase, analytical schemes were evaluated using tracer spikes of approximately 200 alpha cpti ITp̂ "̂̂ "because this level of activity was best suited to the electronic alplia counting equipment available. The gatEtaa emitting isotope, Ip^^®, vas used in certain cases when a complete material balance through a separation step was desired. As the work progressed, techniques xrere evaluated at lower spike levels using nuclear film track (autoradiographic) counting techniques^' .. An abundance of literature has been published concerning analysis for neptunium. /Roberts^ used nitrate fora anion exchange resin, while Wish and Rowell^'used the chloride form. Moore^' utilised a thenoyltrifluoroacet one-xylene extraction. Eyde^ has reviewed -siany analytical schemes for this element, but none are concerned with urinalysis. Argonae national Labora,tory— describes a procedure for neptunium in urine, but this separation isola-tes americium, curium, plutonium, thorium, and neptunitm as gross alpha, frm procedixre of Perkins^ for neptunium in urine and the %-?ork of Mitchell^^ on elcctrodeposition of the actinides serve as a bacis for the work in this report. Urine media for this investigation was obtained from a composite of routine samples analyzed, by the Industrial Hygiene Laboratory» This was stored in a 9-liter carboy and 5OO -ffll portions were siphoned off as needed. The spike used in the evaluation was 96f» Wg^^"^ by alpha energy analysis. The remaining k^o may Imve been shielded Ip̂ ®"̂ or Th^®°» Evalu.ation of Available Procedm°es Attempts to analyse txrinc for Ip̂ ®"̂ following the procedure of Perkins^ gave recoveries of about 50fj with poor reproducibility. This procedure Eepa,rate3 uranium and plutoniua by double lanthanum fluoride precipitation followed by TTA extraction. Ferrous aianonium suJ-fate and hydrosylanine a.t.e used as redu.cing agents in both steps. leptuniuoi is stripped from the TTA with 8 ̂ HCl. The HCl is evaporated to a low voluiae, made alkaline with KOH, and neptuniuTi is electrodeposited on polished stainless steel discs after adding sodium hypochlorite solution. By u.sirig ip^^^ and counting discard fractions froM each step of this procedTX-'e, it was found that the cheraical separations gave 85-90̂ 3 reco\ery of neptuxiium, while the subsequ,eat electroplating procedure was erratic and gave recovery of ly-'!%^ The method of R. F« Mitchell^' for electroplating plutoniun from aji amraoaiuei chloride solution at pE 1 was tried and Ip recovery of JO-pOfa was obtained»