(6) J. Y. Marks arid G. G. Welcher, 3rd Annual Meetlng, Federation of Analytical Chemistry and Spectroscopy Societies, Philadelphia, Pa., 1976, Paper 176. (7) Bruce R. Culver and Terry Surles, Anal. Chem., 47, 601 (1975). (8) K. C. Thompsen and R. G. Godden. Ans/yst(London). 101, 96 (1976). (9) R. J. Lovett, D. L. Welch, and M. L. Parsons, Appl. Spectrosc., 29, 470 (1975). (10) M. S. Epsteln and T. C. Rains, Anal. Chem., 48, 528 (1976). (11) M. L. Parsons, B. W. Smith, and G. E. Bentley, “Handbook of Flame Spectroscopy”, Plenum Press, New York, 1975. (12) W. F. Meggers. C. H. Corllss, and B. F. Scribner. “Tables of Spectral Line Intenstties”, Parts I and 11, US. Dept. of Commerce, Natl. Bur. Stand. (U.S.) Monogr., 145, 1975. (13) G. R. Harrison, “MIT Wavelength Tables”, MIT Press, Cambridge, Mass., 1969. (14) A. N. Zaidel, V. K. Prokoviev, S. M. Raiskii, V. A. Slavnyi, and E. Ya Schreider, “Tables of Spectral Llnes”, 3rd ed.,IFIIPlenum, New York, 1970. (15) 0. G. Welcher, 0. H. Kriege, and J. Y. Marks, Anal. Chem.. 48, 1227 (1974). (16) M. S. Epstein and T. C. O’Haver, Spectrochim. Acta, Part B. 30, 135 (1975). (17) R. Sydor and G. M. Hleftje, Anal. Chem., 48. 2030 (1976).
(18) M. Kirk, E. G. Perry, and J. M. Arrkt, Anal. Chim. Acta, 80, 163 (1975). (19) R. N. Hager, Jr., Anal. Chern., 45, 1131A (1973). (20) T. C. O’Haver, “Trace Analysis: Spectroscoplc Methods for Elements”, J. D. Winefordner, Ed., Wiley, New York, 1976, Chap. 3. (21) W. R. Kelly and C. B. Moore, Anal. Chem., 45, 1274 (1973). (22) P. L. Larkins and J. B. Willis, Spectrochirn. Acta, Part B, 29, 319 (1974).
RECEIVED for review October 13, 1976. Accepted February 22,1977. From a dissertation to be submitted to the Graduate School, University of Maryland, by A. T. Zander, in partial fulfillment of the requirements for the Ph.D. degree in Chemistry. Presented, in part, at the 3rd National Meeting of the Federation of Analytical Chemistry and Spectroscopy Societies, Paper No. 349, Philadelphia, Pa., 1976. Financial support provided by the National Science Foundation, Grant No. ESR-75-02667 (NSF-RANN). Partial support for one author (P.N.K.) by the Villanova Faculty Research Program is gratefully acknowledged.
Electrodeposition of Plutonium and Americium for High Resolution CY Spectrometry Ivan K. Kressln Industrial Hygiene Group, Health Division, Los Alamos Scientific Laboratory, University of California, Los Alamos, New Mexico 87545
NaHSO,-Na,SO, is used to prepare plates Containing Pu or Am by electrodeposition from pure solutions for high resolution a spectrometry. NaHSO, is added to the sample before any fuming operations to prevent tracer quantities of the actinides from baking onto the beaker during fuming. Na2S04in the Na,SO,-NaHSO, electrolyte acts both as a buffer to maintain a pH of 2 and as an electrolyte to reduce the resistivity of the cell. Because of the Na2S04, no pH adjustment of the eiectroiyle solution is required before deposition Is started, and a uniform pH is maintained during the electrodeposition. The recovery Is 100.9% f 2.0 for Pu and 102.4% f 3.4 for Am when 4 pCI of either actkJde Is electrodeposited. The a energy resolution Is excellent. The electrodeposition is not affected by mg amounts of NO3-, C2042-,and PO4-, but citrate and FInterfere; many metal ions will electrodepodl with the actinide If present In the solution.
High resolution CY spectrometry of Pu and Am requires a very thin and uniform deposit of these elements. a particle sources are usually prepared for CY spectrometry on a flat metal plate such that the possible solid angle for a emission is 2 T steradians. Lucas and Hutchinson (1, 2) have published papers on how to calculate the correction for the disintegrations recorded by a counter having 2 T geometry to the actual disintegrations occurring, and they have presented data to show the agreement between theoretical and experimental results. The ideal plate to determine a activity by a spectrometry would be a flat plate having a monoatomic layer of the actinide and no foreign material above the actinide layer to attenuate the a radiation. Four basic techniques have been used to obtain a thin deposit or film; vacuum evaporation, elec842
ANALYTICAL CHEMISTRY, VOL. 49, NO. 6, MAY 1977
trospraying, painting or stippling with a volatile solvent, and electrodeposition. Electrodeposition is probably the most widely used of the four techniques mentioned and the literature is replete with electrodeposition procedures. Electrolyte solutions containing KOH-K2C03 (3), ammonium formate ( 4 , 5 ) ,NH4C1-HC1 (61, NHICl and NHII (7, €0, NH4C1-H2C204 (9), (“&SO4 (101, isopropanol ( 1 0 , and dimethylsulfoxide (12) have been reported for the electrodeposition of actinide elements. No single electrodeposition method has received universal acceptance although each procedure has some unique features. When an electrolyte contains chloride, chlorine is evolved during the electrodeposition which etches the Pt anode and requires the use of a local exhaust system. The chloride will also etch the stainless steel cathode if it contacts the steel for any length of time before the electrodeposition. Both the Fe and Pt will be redeposited along with the actinide elements, and these non-actinide elements will cause an inferior a spectrum. Boyd (13) has found that as little as 10 pg of Fe is easily visible on a 71 mm2 (3/pin. diameter) plate and that 50 pg will cause serious tailing of the a spectrum. This deposit decreases the reliability of the results, especially if more than one isotope is to be determined in a single sample. It has been reported (14) that the presence of oxalate in the electrolyte will suppress the electrodeposition of Fe, a common contaminant in most samples, but oxalate ion also inhibits the deposition of P u and Am. Talvitie (14) reported a procedure which eliminated chlorides from the sample by fuming with sulfuric acid and then prepared the electrolyte by adjusting the solution to pH 2 with ammonia. This critical pH adjustment requires some practice and is time consuming, but the fuming with H2S04 has the advantage of preventing premature hydrolysis of the actinides. Puphal and Olsen (15) prevented the hydrolysis of actinides before the electrodepositionby fuming the sample
.ESS CAP
Flgure 1. Electrodeposition cell
to dryness in the presence of NaHS04. This laboratory has found that the addition of NaHS04 before fuming prevents actinides from baking onto the beaker during fuming, especially when working with trace quantities (
